MUFFLER LINING FOR AIR OR GAS CHANNELS

Abstract: Muffler lining (1, 2, 3) for air or gas channels, which muffler lining is arranged for being mounted with good sealing in a closed outer casing (4) of sheet metal, plastic or another material, and in which the outer casing (4), as known in the art, is formed with cross ends (5) and with tube studs (6) for mounting of the complete muffler as an intermediate part between air and gas channel parts, and in which the muffler lining comprises an inner muffler element (1) forming a closed flow channel, and which at the interior thereof is connected to an air/gas pervious inner layer (2) of a tensile and abrasion resistant fibre or fabric material, for instance a glass fibre fabric or a glass fibre mat, and an outer muffler element (3) which completely encloses the inner muffler element (1). The inner element (1) is made up of parallellepipedical lamellae (8) of mineral wool having a thickness of more than 5 mm, which when forming the inner element to a closed unit form outwardly facing V-shaped slots (10). The outer element (3) can be formed as two or more parts providing an enclosing unit, or as a tube shell, which completely encloses the inner element.

Description: MUFFLER LINING FOR AIR OR GAS CHANNELS The present invention relates to a muffler lining for air or gas channels, which is arranged for being mounted, with good sealing, in a closed outer casing of sheet metal, plastic or another stiff material thereby forming a complete muffler, whereupon said complete muffler can be mounted as an interconnection part between air or gas channel parts Mufflers or sound absorbers for air or gas channels are known in many various designs A usual type of sound absorber for air or gas channels comprises an inner, perforated sheet metal tube, round which a muffler mat has been mounted, sometimes with a blocking layer round the muffler mat, and in which the unit comprising the sheet metal tube, the eventually existing blocking layer and the muffler mat has been enclosed in an outer tube Among other things the said type of muffler involves the disadvantage that the inner sheet metal tube proαuced a non-desired sound of its own Further the said type of muffler also does not provide a particularly good damping of sound in the lower sound frequency areas Often sound in the low frequency and medium frequency areas are the most disturbing sounds for the ambient and the sound, which is most desirable to dampen as effectively as possible. Another type of muffler is formed with a muffler element in the form of a semi cylinder shaped tubular shell of mineral wool which is exteriorly surrounded by a sheet metal layer, and in which two pieces of muffler elements which have been joined to each other provides a complete muffler together with the sheet metal layers A muffler of this type can leak air or gas in the joint between the two semi cylinder shaped units, and the manufacture of the muffler comprising the two semi tubular shells and the sheet metal layer is expensive, in particular since the muffler units have to be manufactured in several specific dimensions adapted to match the dimensions of the air or gas channels Attempts also have been made to manufacture mufflers from mineral wool plates which have been formed with V-shaped recesses extending at least some distance into the mineral wool plate but not completely through same and slong which V-snaped recesses the plate has been bowed to round shape with the recesses facing inwards, whereupon the tube manufactured by the mineral wool plate has been enclosed in some type of outer sheet metal or plastic casing With this type oτ muffler liner there can be a risk that the liner collapses or falls together thereby more or less choking the flow of air or gas through the air/gas channel It is also difficult to clean the air/gas channel without having the cleaning Drush or cleaning scraper stick to the muffler material and perhaps tear off parts thereof during the cleaning. The said priorly known muffler further involves the serious disadvantage that it is normally not possible to perform a cleaning and scraping off dust and other particles therefrom, which dust and particles irrevocably stick to the inner surface of the inner muffler element. From health viewpoint it is important that dust and other particles which have stuck to the muffler and to the air/gas channel is removed at frequent intervals, so that said dust or particles is not blown out into the room in which humans or animals stay. The present invention therefore is intended to solve the disadvantages and lacks in priorly known mufflers for air or gas channels and to provide a muffler liner - which gives an optimum dampening of sound over substantially the entire frequency area, and in particular in the low-to-medium frequency sound areas, - which is formed so that none of the parts thereof create any sound of its own, - which is formed so that the muffler lining can simply be manufactured with any desired dimension (length and diameter) and with any desired cross section shape (e.g. circular, elliptic, polygonal), - which can easily be adapted to any dimension of air or gas channels, - which is formed so that there is no risk that said lining collapses inside the outer casing of the muffler, - which consists entirely of non-inflammable materials, - and which, in front of all, can be repeatedly cleaned from dust and other particles which have stuck to the inner surface of the muffler channel. According to the invention the muffler comprises a lining which is composed of - several lamellae of a fibre material, - which lamellae are fixed edge to edge to each other on a sound dampening inner layer of a relatively thin material which is air pervious, and which has a high mechanical tensile strength and abrasion strength, - whereupon the inner layer with the lamellae have been formed to a tube with the lamellae facing out from the relatively thin air pervious material and with the V-shaped formations, formed when the lining is bowed to round shape, facing outwards, - and in which the lamella tube with its relatively thin inner layer has been enclosed in a tube or a tubular shell of a sound dampening type, for instance a tubular shell of mineral wool having such dimension that it is completely closed in its mounted condition, - and in which the muffler lining comprising inner layer-lamella shell-outer tubular shell has been enclosed, as known per se, in an outer casing of sheet metal, plastic or a similar material and formed with connection studs for air or gas channels. Further characteristics of the invention will be evident from the following detailed specification, in which reference will be made to the accompanying drawings, which show an embodiment of a sound muffler according to the invention. In the drawings figure 1 shows an example of a muffler which, as known in the art, is mounted as an intermediate part between two spaced channel pieces. Figure 2 shows a vertical cross section through a muffler according to the invention, as seen along line ll-ll of figure 1. Figure 3 illustrates a stage in the method of manufacture of an inner lining part of the muffler according to the invention. Figure 4 shows a ready inner lining part in a perspective view, and figure 5 shows a complete muffler lining according to the invention before said muffler lining has been enclosed in an outer casing of sheet metal, plastic of a corresponding material. The muffler according to the invention comprises a inner muffler element 1 which at the interior thereof carries a relatively thin sound dampening inner layer 2, and an outer muffler element 3 of a sound dampening material, for instance mineral wool, which material entirely, and with good contact between the units, encloses the muffler element 1 , and in which the unit of inner muffler element 1 , inner layer 2 and outer muffler element 3 is enclosed, as conventional, in an outer casing 4 of sheet metal, plastic, or a similar material. Said casing is formed with transverse ends 5 and tube studs 6 connected thereto for sealingly mounting of channel parts 7 thereto. The tube studs 6 preferably are formed with inwards to the inner of the muffler element facing short tube pieces 6a which keep the muffler lining together and prevents a collapsing thereof. Alternatively the muffler lining can, for the same purpose, be formed with separate short tube pieces at its ends. The inner muffler element 1 is made as a plain unit consisting of several lamellae 8 of a sound dampening material having the desired sound dampening properties, for instance mineral wool of a predetermined density giving an optimum sound dampening. The lamellae 8 have a total width which is adapted so that a ready, closed inner element 1 , as shown in figure 4, forms a substantially closed unit, which can be circular cylindrical, as shown in the figures, or which can have an oval, elliptical, polygonal or any other cross section shape. For an air/gas channel having a diameter of about 250 mm the inner muffler element 1 made of the lamellae 8 can have a thickness of e.g. between 9 and 20 mm and a lamellae width of 60-75 mm. The lamellae should be of such width that the risk that the inner element 1 collapses inside the muffler is eliminated. This is also accomplished in that tube studs at the ends of the muffler extends some distance into the inner of the muffler element 2 with stud pieces 6a, or that the muffler, at each end thereof, has a short inner ring which prevents the lamellae 8 from collapsing inwardly in the muffler. The lamellae are secured to a plain inner layer 2 which can be an air pervious material which preferably also is of a type which can give a certain contribution to the sound dampening, for instance a glass fibre fabric having a volume weight of more than 100 g/m 2 , and which has a high tensile and tear resistance for enabling a frequent brushing and cleaning of the muffler, even by means of mechanical means like scrapers and brushes, without damaging the inner layer 2, and without scraping of brushing up the inner layer and without releasing particles of said inner layer. The lamellae 8 are applied by being sewed, by being glued or by being fixed to the inner layer 1 in a corresponding way. The inner layer 2 is preferably wider than the combined width of the lamellae 8 and it is used for interconnecting the ends of the muffler element in that the projecting ends 9 of the inner layer 8 are pulled radially outwards some distance outside the end lamellae so that said projecting end pieces 9 can be stitched together thereby keeping the longitudinal ends of the inner element together after the inner element 1 has been fold in to form a closed unit. From fire protection viewpoints, and considering the possibility of cleaning the muffler by means of a brush or a scraper it is important that the inner layer 1 closes the unit of inner layer 1 and lamellae together in this way to form a well closed unit. After the lamellae 8 have beein fixed to the inner layer 2 the element 2, 8 is fold round with the lamellae 8 facing outwards, whereby there appear V-shaped slots 10 between the longitudinal edges of the lamellae, whereas the inner edges are in direct contact with each other. Of course the inner element 1 , and thereby the entire muffler, can be formed with any other cross section shape than circular cylindrical, for instance with oval, polygonal like square (4), hexagonal (6) etc. cross section shape for adapting the muffler to the shape and the function of available air/gas channels. When the inner element has been formed, as mentioned above, to a cylindrical or other type of shape the inner element 1-2 is enclosed in an outer muffler element 3 which can be two semi tube shells, or still better a complete, slotted 11 tube shell. The slot 11 of the tube shell 3 preferably is located midway of a lamella 8 for eliminating the risk that eventually occurring fire is spread through the air/gas channels. The entire muffler lining comprising the inner muffler element 1 comprising the inner layer 2 and the lamellae 8, and the outer muffler element 3 is now enclosed in an outer casing 4 which can be of sheet metal, plastic or any other stiff material, and which has cross ends 6 which can carry tube studs 6 for connection of the muffler to cross cut ends 7 of the air/gas channel. As previously mentioned said tube studs 6 can have a short ring 6a extending inwards in the muffler element and which keeps the inner layer 1 held outwards thereby preventing a collapsing thereof. Thanks to the above described embodiment of the muffler there is obtained the important advantage that the muffler can repeatedly be cleaned and can be released from dust and other particles which are collected on the inner layer, and this can be done without having the cleaning scraper stick to the joint of the inner layer, and without having parts of mineral wool or any other dampening material becoming brushed or scraped off. REFERENCE NUMERALS 1 inner muffler element 2 inner layer 3 outer muffler layer 4 outer casing 5 cross end 6 tube stud 6a end piece / ring 7 air/gas channel pieces 8 lamellae 9 projecting ends (of 2) 10 slots 11 slot

Claims: C L A I M S 1. Muffler lining for air or gas channels adapted for being mounted with good sealing in a closed outer casing (4) of sheet metal, plastic of another material, and in which the outer casing (4), as known in the art, is formed with cross ends (5) having tube studs (6) for mounting of the complete muffler as an intermediate part between air or gas channel parts (7), characterized in that the muffler lining comprises muffler elements (1) forming a closed flow channel, and which over the interior thereof carries an inner layer (2) of a tensile strength and abrasion resistant fibrous material or a fabric material, and an outer muffler element (3) which completely surrounds the inner muffler element. 2. Muffler lining according to claim 1 , characterized in that the inner muffler element (1) is built up by longitudinal lamellae (8) of a sound dampering material. 3. Muffler element according to claim 2, characterized in that the lamellae (8) have a parallelepipedical cross section shape and engage each other edge to edge at the inner surface of the inner element, whereby said inner element, after it has been formed to a closed unit exposes outer V-shaped slots (10) between the lamellae (8) in the ready muffler lining. 4. Muffler lining according to any of the preceding claims, characterized in that the outer muffler element (3) is made of two or more parts forming an enclosing unit, or it comprises an integral tube shell which is preferably slotted (11) along a longitudinal line, or it is a mat which has been formed to an enclosing unit. 5. Muffler lining according to any of the preceding claims, characterized in that the inner layer (2) inside the inner muffler element (1) is made of an air and gas pervious fabric, like glass fibre fabric or a glass fibre mat. 6. Muffler lining according to claim 5, characterized in that the glass fibre fabric or mat (2) har a volume weight of mor than 100 g/m • 7. Muffler lining according to any of the preceding claims, characterized in that the inner muffler element (1) is made of lamellae (8) of mineral wool having a thickness of more than 5 mm, preferably a thickness of between 5 and 20 mm. 8. Muffler lining according to any of the preceding claims, characterized in that the outer muffler element (3) comprises a tube shell of mineral wool having a thickness of more than 20 mm, preferably a thickness of between 20 and 50 mm. 9. Muffler lining according to any of the preceding claims, characterized in that the unit comprising the inner layer (2), the inner muffler element (1) and the outer muffler element (3) is enclosed in an outer casing (4) of sheet metal, plastic or a correspondingly stiff material and is formed with cross ends (5) having axially outwards projecting tube studs (6) for connecting thereof to air/gas channel pieces (7). 10. Muffler lining according to claim 9, characterized in that the inner element (1 , 2) and a short length adjacent its ends has an inner supporting ring (6a) which can be a separate ring or an inwards projecting part of the cross ends (5) with the tube sutds (6). AMENDED CLAIMS [received by the International Bureau on 28 August 2000 (28 08.00) ; original claims 1 replaced by amended claim 1 ; original claims 2 and 3 cancelled; original claims 4 - 10 renumbered as claims 2 - 8 (2 pages)] 1. Muffler lining for air or gas channels adapted for being mounted with good sealing in a closed outer casing (4) of sheet metal, plastic of another material, and in which the outer casing (4), as known in the art, is formed with cross ends (5) having tube studs (6) for mounting of the complete muffler as an intermediate part between air or gas channel parts (7), characterized in that the muffler lining comprises an inner muffler element (1) of mineral wool forming a closed flow channel, and which over the interior thereof carries an inner layer (2) of a tensile strength and abrasion resistant fibrous material or a fabric material, and an outer muffler element (3) which completely encloses the inner muffler element (1), and in which the inner muffler element (1 ) is built up by longitudinal lamellae (8) of mineral wool, and in which said lamellae (8)have a parallelepipedical cross section shape and engage each other edge to edge at the inner surface of the inner element (1), whereby there are formed, after said inner element (1 ) has been fold together to a closed unit, outer V-shaped slots (10) between the lamellae (8) in the ready muffler lining. 2. Muffler lining according to claim 1 , characterized in that the outer muffler element (3) is made of two or more parts forming an enclosing unit, or it comprises an integral tube shell which is preferably slotted (11) along a longitudinal line, or it is a mat which has been formed to an enclosing unit. 3. Muffler lining according to claim 1 or 2, characterized in that the inner layer (2) inside the inner muffler element (1) is made of an air and gas pervious fabric, like glass fibre fabric or a glass fibre mat. 4. Muffler lining according to claim 3, characterized in that the glass fibre fabric or mat (2) har a volume weight of mor than 100 g/m ■ 5. Muffler lining according to any of the preceding claims, characterized in that the inner muffler element (1) is made of lamellae (8) of mineral wool having a thickness of more than 5 mm, preferably a thickness of between 5 and 20 mm. 6. Muffler lining according to any of the preceding claims, characterized in that the outer muffler element (3) comprises a tube shell of mineral wool having a thickness of more than 20 mm, preferably a thickness of between 20 and 50 mm. 7. Muffler iining according to any of the preceding claims, characterized in that the unit comprising the inner layer (2), the inner muffler element (1) and the outer muffler element (3) is enclosed in an outer casing (4) of sheet metal, plastic or a correspondingly stiff material and is formed with cross ends (5) having axially outwards projecting tube studs (6) for connecting thereof to air/gas channel pieces (7). 8. Muffler lining according to claim 9, characterized in that the inner element (1 , 2) and a short length adjacent its ends has an inner supporting ring (6a) which can be a separate ring or an inwards projecting part of the cross ends (5) with the tube sutds (6).

Inventors: PETTERSSON LEIF, PETTERSSON, LEIF
Applicants: PAROC AB, PETTERSSON LEIF, PETTERSSON, LEIF
Application year: 2000
Main classification: F16L55
IPC codes: F16L55, F24F13