WO2005049982A1

WO2005049982A1 - Sock-shaped fabric element, used for containing sound absorbent material

Info

Publication number: WO2005049982A1
Application number: PCT/IT2003/000763
Authority: WO
Inventors: Luigi Pianese
Original assignee: Vale S.R.L.
Priority date: 2003-11-21
Filing date: 2003-11-21
Publication date: 2005-06-02
Also published as: AU2003292535A1; EP1711694A1

Abstract

A flexible tubular element is disclosed, which has the shape of a sock or stocking and is entirely realized by means of a single glass fibre yarn, and which, furthermore, is suited to contain a bulky mass of glass wool as sound absorbing material used in silencers of explosion engines. This stock-like element is capable of expanding during normal use of the motor to be soundproofed; moreover, it can be realized in the form of a ready-made finished product even outside the place where it is actually introduced into the silencer. Furthermore, said lock-like element keeps an extreme flexibility and adaptability even after filling with the required quantity of expanded glass fibres, so as to perfectly fill the irregularly shaped spaces that are present inside the mufflers.

Description

Sock-shaped fabric element, used for containing sound absorbent material

Technical Field of the Invention

The present invention can be applied for limiting environmental noise produced during normal use of explosion engines. Sound pollution is one of the main problems related to the use of public and private vehicles provided with internal combustion engines, regardless of whether .the combustion cycle is a four-stroke or two-stroke cycle, and regardless of the utilised fuel. In order to reduce the intensity of sound generated by the exhaust gases of motorcycles, automobiles, vans, lorries, buses etc., the law imposes the use of sound deadening plants mounted at the exhaust terminals, so as to limit acoustic perturbations within values complying with the regulations. The present invention lends itself extremely well to this utilisation, simplifying the assembling, increasing the sound deadening effect, and reducing costs. Silencers of vehicles equipped with internal combustion engines are provided since long time with deadening apparatuses, so-called mufflers, which are suited to absorb the noise produced inside the cylinder explosion chamber. The form of these mufflers is very irregular, since they must be wedged in the free spaces of the lower part of the vehicle, and since they must also comply with physical laws relating both to motor efficiency and to acoustic waves absorption and propagation.

Background Art Since many years mufflers of vehicle silencers are produced by filling up the sound deadening bodies with sound absorbing material. This sound absorbing material is essentially a low-density polymer, usually fibre glass, which is able to absorb acoustic perturbations and has - at the same time - a high melting point to withstand the high operating temperatures that develop inside the exhaust tube, due to the high temperature of the combustion gases. There exist various techniques for introducing said sound absorbing, loose material, into apposite spaces made available inside the silencers. One of these methods consists in filling up these spaces with said sound absorbing material, and in preventing its escape by means of a material enclosing fabric. This method, to be applied before closing the silencer, is time consuming, inefficient, and susceptible of variations in the application and density of the same sound absorbing material, so as to influence the final soundproofing effect. A further method provides for the introduction - while the silencer is still open - of solid shells of sound absorbing materials. This method is very effective but it is much more expensive than the former one. A third method consists in directly blowing the sound absorbing polymer into the selected space of the silencer, while the latter is in its closed condition. This method requires considerable additional costs, specific machines to carry out this blowing- in operation, and consequently a considerable complication of the conveyer (production line).

Disclosure of Invention

The present invention aims at improving the previous methods, by providing a concrete, practical, and economic solution to the problem of the handling of soundproofing materials, and in the specific case, of fibre glass, to be introduced in the silencers of explosion engines. The present invention, through the introduction of the innovative use of a tubular sock-like (or stocking-like) element formed by a single glass fibre yarn, which is simply interlaced (braided) but not welded or knotted, substantially changes the previous state of the art by noticeably simplifying the operations required to obtain soundproofing in silencers of explosion engines.

Brief Description of Drawings

Fig. 1 is a side view of the sock-like element (1) made of glass fibre, according to the present invention, filled with sound absorbing material (2), that is, expanded glass fibre.

Fig. 2 is a side view of the sock-like element (1) made of glass fibre, without the inner soundproofing material.

Fig. 3 is a front view of the sock-like element (1) according to the present invention, highlighting the end clamping region (3) of the sock-like element, which serves to prevent a loss of the sound absorbing material (2) contained therein.

Fig. 4 is an enlarged view of the woven structure (4) that forms the sock-like element itself.

Best Mode of Carrying out the Invention The sock-like element ( 1 ) is formed of a single yarn, which is typical of a knitting process (4), said yarn being repeatedly interlaced on itself so as to assume the desired three dimensional shape, thereby avoiding the use of knots or welding points. A desired amount of glass fibres (2) is introduced inside said sock-like element (1), according to the features of the corresponding motor, by appropriately calibrating this amount in accordance with the muffler to be produced. A peculiar feature of this sock-like element (1) resides in the fact that it does not have knots in its structure, and in that it is entirely realised by means of a glass fibre yarn, which is exactly the same material forming the bulky sound absorbing mass introduced in the sock-like element. This feature allows, after starting the motor, an automatic expansion of the sock-like element itself. This expansion process of the sock-like element or bag (1), which is ascribable to the absence of knotted or welded (melted) clamping points, occurs only as a consequence of the existing pressures and vibrations generated by the normal operation of any kind of explosion engine. Therefore, through a normal use of the vehicle motor it is possible to obtain a progressive expansion of the whole sock-like element (1), which, while not loosing its retention properties, becomes an integral part of the sound absorbing mass, thereby improving - simply through the motor operation - the sound deadening properties of this kind of silencer.

Furthermore, since the sock-like element (1) is extremely soft, due to the intrinsic features of its constituent component (the yarn), even when it is filled of glass fibres, it keeps its peculiarity of being extremely handy and substantially devoid of any fixed geometric form, so that it can easily reach all gaps and convexities existing in the mufflers of the silencers. A further advantage of the use of this sock-like element (1) of the present invention is that it can easily change its diameter and its total length, thereby being perfectly adaptable to any sort of silencer to be soundproofed.

Industrial applicability The extreme easiness of realisation inherent in this invention allows to obtain finished, prefabricated sock-like elements, to be introduced - already filled with expanded glass fibre - inside silencers to be soundproofed. All these operations must take regard of the strict density and volume specifications established from time to time by technicians. A further advantage of the present invention resides in the low cost of the whole ready-made sound absorbing material to be introduced inside the silencers to be soundproofed. The cost reduction of the realisation according of the present invention resides in the extreme practicality that the handling of a finished and versatile product allows to industrial processing. The exclusive use of glass fibres, being perfectly compatible with the high operating temperatures of silencers and not giving rise to toxic emissions, is the ideal solution for preventing any kind of environmental pollution, or problems due to toxicity phenomena deriving from the formation of volatile and noxious by-products. The above described invention can also be realised in departments or factories that are external to the place where the finished product is actually introduced into the silencer to be soundproofed; in this way, the installation will be simple and quick and will not require additional areas, manpower and facilities.

Claims

1. A sock-like element made of glass fibre, characterised in that it is formed of a single, interlaced yarn, that may assume a three dimensional configuration which is shapeless under a strictly geometrical point of view, said sock-like element being suited to contain therein an expanded glass fibre mass.

2. A sock-like element according to claim 1, wherein its base structure does not include knots or welding points.

3. A sock-like element according to claim 1, wherein the glass fibre yarn used to weave the sock-like element, is itself capable of expanding under the action of the sole pressure caused by the normal operation of the motor to be soundproofed, thereby unifying the retention and soundproofing functionality.

4. A sock like element according to claim 1, wherein said sock-like element, even after it has been filled with sound absorbing material, preserves optimal characteristics of handiness and adaptability, and is easy to introduce inside irregularly shaped cavities that are present inside exhaust silencers.

5. A sock-like element according to claim 1, wherein its dimensions are variable in length and diameter according to the required soundproofing mass.

6. A sock-like element according to claim 1, whose production, filling, and closing, may occur at the time of its installation, or before, thereby allowing in the latter case to deal with a finished product that may be introduced as such inside the silencer to be soundproofed.

7. A sock-like element according to claim 1, wherein this sock-like element is entirely formed of glass fibre and is filled and sealed using the same material.