GB2090912A

GB2090912A - Panel for multi-panel ventilation duct sound absorbers

Info

Publication number: GB2090912A
Application number: GB8136750A
Authority: GB
Original assignee: G&H Montage GmbH; Gruenzweig und Hartmann AG
Current assignee: Saint Gobain Isover G+H AG; G&H Montage GmbH
Priority date: 1980-12-22
Filing date: 1981-12-07
Publication date: 1982-07-21
Also published as: NL8105597A; CH656922A5; FR2496735B1; DE3048560A1; AT379433B; ES508153A0; FR2496735A1; BE891548A; ES8301322A1; ATA495481A

Abstract

A panel wall 1 is bent at its leading and trailing ends to define with a further similar wall 2 or a flat wall a cavity which is filled with sound absorbing material 10. Walls 11 define the ends of the cavity and form reinforcing bulkheads intermediate these ends. The various walls are connected by rivetting or crimping. <IMAGE>

Description

SPECIFICATION Panel for multi-panel sound absorbers and method for its production This invention relates to panels for multi-panel sound absorbers of the type (hereinafter referred to as "the type described") in which substantially rectangular panels are arranged face to face in a stack, usually with the panels disposed in vertical planes, with an intervening space between one panel and the next through which air can flow.

Such sound absorbers are used extensively, inter alia, in ducting in air conditioning systems, and comprise outer walls of acoustically transparent (e.g. perforated) sheet or plate between which is disposed a filling of a sound absorbing material, usually a mineral fibre, with, if necessary, a retaining envelope of, say, glass fleece, to stop the mineral fibres falling through the perforations in the outer wall.

To make known panels, a channel section strip is bent into a rectangular frame which is closed on one face by an acoustically transparent cover, for example, a perforated plate, and thus has the form of a dish-shaped container, which is filled with sound absorbing material such as mineral fibres.

Then the opposite, upper face is closed with a corresponding perforated plate, of which, because of restricted accessibility to the fastening locations, the fastening of frame to perforated plate is effected by spot welding or rivetting. The inner faces of the perforated plates can be provided with a suitable covering, such as a glass fleece, to stop the mineral fibre material falling out. After this, at least the upstream edge of the so-formed panel is provided with a streamlined, preferably rounded fairing to reduce air resistance.

The manufacture of such panels is comparatively labour intensive. Furthermore, the known panel can only be made up to a certain size for reasons of stability. Should larger panels be required, a plurality of such panels must be arranged one above the other in the plane of the panels and mechanically fastened together by rivetted or bonded corner brackets or the like, the upstream edge, however, being able to be covered only after installation by a continuous fairing arranged over all the connected panels.

In particular such a large panel, built up from a plurality of individual panels, is, mechanically, relatively unstable, as a certain play or movement at the fastening locations is unavoidable, and, once this play is taken up, resistance to deformation is effected by the panel elements, in which the perforated plate has to stiffen and support the frame which is itself not very rigid against warping.

In comparison, the invention is based on the problem of providing a panel of the type described, with which, in particular with large panel dimensions, manufacturing and installation costs can be reduced and which can, even with reduced installation costs, be made more stable.

The invention comprises a panel for multi-panel sound absorbers of the type described, comprising at least one outer wall bent at opposite edges into a trough shape so that the said edges can be fastened to the other outer wall so as to leave an internal space for the sound absorbing material.

The separate peripheral frame can thus be completely dispensed with, the spacing for the thickness of the sound absorbing material resulting directly from the turning-in of the outer wall or walls. The need to interpose a side member in a relatively unstable frame is avoided, and the stability is improved and the installation costs are also reduced as a result of the method of manufacture. By incorporating an acute angle between the adjacent outer walls at the upstream and downstream edges the need to provide a fairing is completely eliminated, since the region where the two outer walls are connected can be made suitably streamlined.By this feature, at the same time, the sound absorbing surface area is increased at the edge of the panel, which formerly was covered by a fairing and ineffective for sound absorption, in as much as (in the conventional design) the covering plate was not also formed as a perforated plate and backed by sound absorbing material, which would be costly. As a result of the improvement in stability, it is possible to produce large area panels without going to separate panel elements; where necessary, additional support plates, in the form of ribs or bulkheads at different levels between the two half-shell form outer walls, can be arranged as required.The whole construction, compared with previous panels built up from panel elements, apart from reducing the installation costs of using panel elements, is also lighter, as even when reinforcing bulkheads are arranged instead of horizontal side pieces of the panel element frames, in any event the vertical frame side members as well as the fastening means for the panel elements can be dispensed with. Despite this saving in weight, the panel is nevertheless altogether more stable, as the cumulative play within the panel elements on the other hand and between the panel elements on the other hand is eliminated and also through the direct connection of the outer walls an enhanced stability of shape is effected.

Further details, features and advantages of the invention will appear from the following description of an embodiment shown in the drawings, which show:- Fig. 1 a partly broken away side view of a panel according to the invention Fig. 2 a plan of the panel of Fig. 1 Fig. 3 a section through the panel of Figs. 1 and 2 along the line Ill-Ill of Fig. 1 with parts shown to a larger scale, one in the section and one outside Fig. 4 the detail, to a larger scale, of region IV of Fig. 2 in the neighbourhood of the joint, in section Fig. 5 a plan view of a blank, before bending, for forming a bulkhead for the panel of Figs. 1 to 4 Fig. 6 a section through the now bent blank along line VI--VI of Fig. 5.

As the drawings illustrate, a panel according to the invention and of the present exemplary embodiment comprises in essence two preferably identical outer walls 1 and 2 arranged mirrorimage wise to each other, which on the upstream edge indicated by arrow 3 and also on the opposite downstream edge, are turned in towards each other at an angle a of, for example, less than 450 over a gentle rounded section 4 and meet at an acute angle P in the plane of symmetry 5 of the panel, after the fashion of half-shells (Fig. 4).In the region where they join, in the plane of symmetry 5, the two outer walls, which as shown in Fig. 1, upper left, and also in the sectional view of Figs. 3 and 4, are formed as perforated plates with connecting flanges 6 (see especially Fig. 4), are arranged parallel to one another and lie against each other in the plane of symmetry 5. The connecting flanges 6 are held together by clamp beading 7, which grips both sides of the connecting flange 6 and is secured for example by rivets 8 (see Fig. 1). On the inside, the perforated plate outer walls 1 and 2, as shown schematically in Fig. 3, are provided with a lining, for example in the form of a glass fleece 9 in order to contain, in the-hollow space between the walls 1 and 2, a sound absorbing material 10 (see Fig. 3) that fills up the space, preferably one based on mineral fibres.

As is apparent without further explanation, the illustrated special form of the outer walls 1 and 2, their identical form and mirror-image symmetrical arrangement, yields, besides advantages in manufacture, as a result of their respective turning in towards the plane of symmetry 5, a streamlined formation at the upstream and downstream edges, without requiring separate perforated plates or the like for this purpose. Moreover, these upstream and downstream edge portions participate in the sound absorption, since sound absorbing material 10 is also deployed here. It is, however, apparent that such a symmetrical arrangement of the outer walls 1 and 2 is not strictly necessary, but instead one of the outer walls 1 and 2 might be bent towards the plane of the opposite outer wall and fastened to it there as required.This could be of especial interest for the outer panels of a noise filter, in which also one of the outer walls 1 and 2 can be dispensed with altogether so that the outer side wall of the filter assembly can lie in the plane of symmetry 5. Also for the panels lying at the interior of the filter it would be quite conceivable to arrange the upstream and downstream edges formed by the connecting flanges 6 either similarly or alternately with regard to the plane of symmetry. The illustrated symmetric arrangement results, however, in addidition to manufacturing advantages, a streamlined and also stable shape, as the edge regions of the outer walls 1 and 2 which are bent towards one another have substantial rigidity.

On the upper and lower edges that run parallel to the flow direction as shown by the arrow 3, the hollow space enclosed by the outer walls 1 and 2 and filled with sound absorbing material 10 is closed off or divided by end plates and bulkheads 11, which can be wholly or partly made also of perforated plate, as is apparent from Figs. 2, 4 and 5. In Fig. 5 is shown a blank for making such an end plate or bulkhead, which has lateral, lengthwise-extending edge flanges 12 and also endwise edge flanges 1 3 in connection with the rounded part 4 of the outer walls 1 and 2, all these being bent at substantially right angles to the plane of the blank 11 (Fig. 6) and serving for connection to the corresponding edge regions of the outer walls 1 and 2.This is seen especially in Figs. 3 and 4, in which the overlapping of the edge flanges 12 and 13 with adjacent edge strips of the outer walls 1 and 2 is especially apparent. For the connection between the edge flanges 12 and 1 3 and the outer walls 1 and 2, a rivetted connection 8 can be used as shown in Figs. 3 and 4, as can also a connection by means of the clamp beading 7 with the connecting flanges.

In particular advantageous manner different constructional forms, however, allow a connection of the parts lying face to face by crimping, in which substantially conical projections are formed which lie in corresponding depressions pressed in one operation in the adjacent part and so prevent relative movement of the parts by a bolt-like connection.

In particularly advantageous manner known connection by crimping as also connections through rivets can be used in places in which the outer walls 1 and 2 have in any event existing apertures such as perforations with a diameter of 5 mm. In the case of a rivet connection, this avoids the need to drill the outer walls 1 and 2, while in the case of a crimping operation the material of the adjacent edge flanges 12 or 13 or the adjacent sides of the clamp bead 7 can be pressed into such a hole with reduced force requirement and I;titer locking effect. In all cases the need for welding is avoided by a rivetted or crimped fastening, which avoids damage to any corrosion resistant surface finish on the outer walls 1 or 2 and the end plates 11.

The end plates 11 at the two short ends serve to effect an optimal rigidity of the hollow body formed from the outer walls 1 and 2 and end plates 11 for containing the sound absorbing material 1 0. The thrust forces in the flow direction (arrow 3) act directly on the shape-retaining outer walls 1 and 2 and these are supported in turn by the end plates and bulkheads 11 to be substantially free of play. This shape-retaining construction permits even very large panels to be made in one piece. So the panel seen in Fig. 1 could have a breadth of about one metre and a height of about four metres. Through the large vertical spacing of the end plates 11 , there is, however, a large bending length of the faces of the outer walls 1 and 2 if they are more than 4 metres high, so that with a thrust loading, at first a bowing out of the large area outer walls 1 and 2 is to be expected, even if only with quite high thrust loadings. Further to improve the stability, more bulkheads 11 can be inserted at levels between the end plates 11, at a vertical spacing of about one metre, which stiffens up the construction quite considerably.

In the production of a panel according to the invention like the embodiment illustrated in the drawings, first the perforated plates for the outer walls 1 and 2 are produced by bending, which, in the illustrated embodiment requires those for both outer walls 1 and 2 to be made similar. Then, in this exemplary case, the lower outer wall 2 is fastened to the required number of end plates and bulkheads 11 with bent-out edge flanges 12 and 1 3 by crimping or rivetting and laid on a base with the bulkheads pointing upwards so that a substantially dish-shaped receptacle is provided for the sound absorbing material 10, which is in the form of a mineral fibre, with which the receptacle is filled. Then a further perforated plate for forming in this case the upper outer wall 11 is laid on top and secured by means of the clamp beading 7 by rivetting or crimping. Further operations such as the addition of fairings are not required. Furthermore, in the manner described, the one piece panel can be made to such a size as would previously require assembly from individual panels, which brings quite substantial advantages in assembly and in addition leads to a simpler construction with higher stability.

Claims

1. A panel for multi-panel sound absorbers of the type described, comprising at least one outer wall bent at opposite edges into a trough shape so that the said edges can be fastened to the other outer wall so as to leave an internal space for the sound absorbing material.

2. A panel according to claim 1, in which the edges of the said one outer wall are bent at an acute angle with respect to the general plane of the said outer wall.

3. A panel according to claim 1 or claim 2, in which the edges of the said outer wall are bent in the form of an S-curve.

4. A panel according to any one of claims 1 to 3, in which the said other outer wall is similar to the said one outer wall.

5. A panel according to any one of claims 1 to 3, in which the said other outer wall is a plane sheet.

6. A panel according to claim 5, in which the said plane sheet is part of the outer casing of a multi-panel sound absorber.

7. A panel according to any one of claims 1 to 5, in which the outer rims of the two outer walls are clamped together by a clamping member.

8. A panel according to one of claims 1 to 7, in which the outer rims of the two outer walls are fastened together by rivets.

9. A panel according to any one of claims 1 to 8, in which the outer rims are fastened together by crimping.

10. A panel according to any one of claims 1 to 9, in which the edges that are not bent are closed off by end plates.

11. A panel according to any one of claims 1 to 10, comprising internal reinforcing ribs or bulkheads running from one bent edge to the other.

12. A panel according to claim 10 or claim 11, in which the end plates and/or reinforcing ribs or bulkheads are provided with flanges by which they are fastened to the outer wall or walls as by rivetting.

13. A panel for muiti-panel sound absorbers substantially as hereinbefore described with reference to the accompanying drawings.

14, A method for producing a panel for multipanel sound absorbers of the kind described, comprising the steps of forming a dish- or troughlike outer wall by bending opposite edges of a plane sheet of wall material, placing the wall so that it is open at the top and filling the so-placed outer wall with sound absorbing material, then closing the top.

1 5. A method according to claim 14, in which the edges of the said dish- or trough-like outer wall that are not bent are closed off by end plates prior to filiing with the sound absorbing material.

1 6. A method according to claim 15, in which ribs or bulkheads running between the said bent edges are fixed to the said outer wall before the wall is filled with sound absorbing material.

17. A method according to any one of claims 14 to 16, in which an inner, sound-absorbing material retaining envelope is placed in position before the said material is introduced and before the top is closed.

18. A method for producing a panel for multipanel sound absorbers of the type described, substantially as hereinbefore described with reference to the accompanying drawings.

1 9. A multi-panel sound absorber of the type described, comprising at least one panel as claimed in any one of claims 1 to 13 or as produced according to any one of claims 14 to 18.