GB2037889A - Internal Combustion Engine Exhaust Systems - Google Patents

Abstract

An exhaust system internal lining includes a multiplicity of pieces of yarn made from fibres resistant to damage or degradation by the exhaust gases each piece of yarn being secured to the lined surface or an adjacent substrate and extending away from the surface. The yarn and substrate may be formed of acrylic, cellulosic, wire, glass or asbestos fibres and the yarn and substrate may be secured by tufting and bonding.

Description

SPECIFICATION Internal Combustion Engine Exhaust Systems There have been many proposals to include sound-insulating materials in internal combustion engine exhaust systems in order to reduce noise emission. For example, exhaust pipes, silencers, and expansion chambers have been lined with sound-insulating material on the inside or covered with such material on the outside. Sleeves, pads, blocks and baffles made of sound-insulating material have been included in the construction of exhaust systems and many examples of such constructions are described in Patent Specifications indexed in Class F1 under the mark B2Y1.

Hitherto, the sound-insulating materials generally used in internal combustion engine exhaust systems have been fibres formed from materials which will not be damaged or degraded significantly by the high temperature of exhaust gases nor significantly subject to chemical attack by components of the exhaust gases. Examples of such fibres, which will for convenience hereinafter be referred to as "resistant fibres", most commonly used are fine metallic wires and mineral fibres such as glass, asbestos, or slag, but other organic and inorganic fibres have been proposed. Most frequently the fibres are compacted as a loose mass, but bonded or felted masses and woven and knitted structures have also been proposed. Such resistant fibers are used in performing the present invention.

One resistant fibre which may be used in performing the invention but which is not known to have been used previously to insulate internal combustion engine exhaust systems is heat treated/cyclized ("blackened") polymeric fibre such as our blackened acrylic fibre sold under the Trade Mark "Grafil O". A flame and heat resistant fabric comprising a base sheet bearing a pile comprising yarn of acrylic or cellulosic fibres which have been converted to a blackened, flameresistant state is the subject of our pending patent application No. 2,014,204A.

As described in that specification, such a fabric may be produced either by forming the pile from a yarn of fibres which are in the blackened state or by forming the pile from a yarn of precursor fibres and subsequently treating the fabric to convert the fibres to the blackened state. The former method is preferred with acrylic fibres and the latter method is preferred with cellulosic fibres.

Both methods are applicable in the production of fabrics which may be used in performing the present invention.

According to this invention an exhaust system for an internal combustion engine includes an internal surface having a lining to be exposed to exhaust gases emanating from the engine, the said lining including a multiplicity of pieces of yarn (as hereinafter defined) made from resistant fibres each piece being secured to the surface or to a substrate adjacent thereto and extending away from the surface.

By a piece of yarn is meant a length of an element produced by a textile process of spinning or twisting fibres? The element may be of "singles" construction (that is one in which the component fibres are simply spun together for example by twisting, interlacing or entangling methods) or may be folded, plied or corded (that is a construction in which two or more singles elements are twisted together or in which two or more folded, plied or corded elements are twisted together).

The pieces of yarn may be separate pieces each individually secured to the said surface or substrate or they may be parts of a number of common lengths of yarn each formed into loops or folds to extend away from the surface or the substrate. In the former case the pieces of yarn may each be secured by one end part to the surface or to the said substrate so that their other ends extend away from the surface. Alternatively, they may each be bent at an intermediate region to define two end portions disposed in a U or V shape and be secured to the surface or to the substrate by the bent intermediate region so that the end portions, which may be of equal or unequal length, extend away from the surface.In the latter case spaced parts of the length of yarn between the parts formed into loops or folds are secured to the surface or to the substrate at closely spaced points so that the loops or folds stand up and extend away from the surface or substrate. The securing of the pieces of yarn to the surface or the substrate may be by bonding or by mechanical locking or by a combination of mechanical locking and bonding.

Conveniently the substrate may be a fabric produced from resistant fibres (as previously defined) by any known method such as weaving or knitting or the bonding of a web of loose fibres.

The pieces of yarn may be bonded to such a substrate fabric in known manner using a bonding material which will not be damaged or degraded or chemically attacked significantly by the exhaust gases to which the lining is to be exposed. Alternatively the pieces of yarn may be included in the structure of such a substrate fabric during its production so that they are mechanically locked into the fabric. Preferably, however, the pieces of yarn are mechanically locked to such a substrate fabric by a process of tufting so as to produce what is more or less a conventional pile fabric akin to a carpet made from resistant fibres.As in conventional tufted carpet production the mechanical locking of the pieces of yarn to the fabric may be reinforced by bonding by coating the back face of the fabric after tufting with a suitable bonding paste, in this case one which when dry will not be damaged or degraded significantly by thermal or chemical action of the exhaust gases. Known tufting processes can produce either a 'cut' pile in which the ends of individual tufts of yarn extend away from the face of the substrate fabric or a 'loop' pile in which the tufts are loops or folds of lengths of yarn extending away from the face of the substrate fabric, each length of yarn being secured to the fabric at closely spaced points by portions of the yarn between the loops or folds.

Both cut pile and loop pile constructions, or a combination of both, can be used in performing the invention.

Thus a preferred exhaust system for internal combustion engines according to the invention includes an internal surface having a lining to be exposed to exhaust gases emanating from the engine, the said lining comprising a substrate fabric having a tufted pile of pieces of yarn extending away from the surface, both the substrate fabric and the pieces of yarn being made from resistant fibres.

The yarn from which the pieces of yarn are formed may be produced from a single kind of resistant fibre (as previously defined) or from a blend of two or more resistant fibres. Where a folded, plied or corded yarn construction is used it may be produced from singles elements made from the same resistant fibre or different resistant fibres or one or more blends of different resistant fibres.

A substrate fabric as described may be secured to the internal surface of an exhaust system by bonding with a suitable bonding material which will be resistant to exhaust gases as previously mentioned or by mechanical means. For example, it could be stitched or riveted to a wall of the exhaust system or its edges could be incorporated in seams of a part of the exhaust system such as the usual rolled longitudinal and end seams in a conventional sheet metal automotive engine silencer.

It will be understood from the foregoing description that the pieces of yarn will normally extend more or less perpendicular to the lined surface of the exhaust system, though they could be arranged to lie at an acute angle to it. They may be of such length that the pieces extending from opposite surfaces of the exhaust system can meet each other when fully extended, but in this case (and in most other cases) the yarn or yarns from which the pieces are made should be sufficiently flexible to the blown aside by the pressure and flow of the exhaust gases when the exhaust system is in operation so as not to cause significant obstruction to the passage of the gases. As previously mentioned the pieces of yarn need not be all of equal length and indeed there may be advantages in using a variety of different lengths.

The following are examples of tufted fabrics which may be used for lining internal surfaces of internal combustion engine exhaust systems: 1. Cut Pile, 36.6 stitches/10 cm, 3.8 cm total tuft length. Pile Yarn - R850 Tex/2, Blackened Acrylic ('Grafil O') Pile Weight 1,890 gm/m2.

2. Cut pile, 36.6 stitches/1 0 cm, 3.8 cm total tuft length. Alternate rows - 1 row - R850 Tex/2, Blackened Acrylic ('Grafil O') 1 row R1,280 Tex/3/3 glass yarn Pile weight 2,090 gm/m2.

3. As example 2 but with needlebar displacement (2x2) to give broken rows. Pile weight 2,160 gm/m2.

4. Cut pile, 35.4 stitches/10 cm, 3.8 cm total tuft length, Pile yarn, R1,280 Tex/3/3 Glass yarn Pile weight 2,560 gm/m2.

5. Cut pile, 37.4 stitches/10 cm, 5.1 cm total tuft length. Pile yarn -- R1,289 Tex/3/3 Glass yarn Pile weight 3,180 gm/m2.

6. Cut Pile, 36.6 stitches/10 cm, 3.8 cm total tuft length. Pile yarn, Blackened Acrylic ('Grafil O') Glass grandrelle yarn R845 Tex. 425 Tex+R420 Tex/3 Pile weight 1,820, gm/m2.

7. Cut Pile, 36.6 stitches/10 cm, 5.1 cm total tuft length. Pile yarn, Blackened acrylic ('Grafil O')/Glass grandrelle yarn R845 Tex; 425 Tex+R420 Tex/3. Pile weight 2,380 gm/m2.

8. Loop Pile, 45.3 stitches/1 0 cm, Alternate rows 3.2 cm and 1.6 cm total loop length. Pile yarn R1,280 Tex/3/3 Glass yarn Pile weight 1,430 gm/m2.

9. Loop Pile, 34.3 stitches/10 cm, 3.2 cm total loop length. Pile yarn R1,280 Tex"'3/3 Glass yarn Pile weight 1,900 gm/m2.

10. Loop Pile, 34.3 Stitches/1 0 cm, High/Low pattern (small repeat). Pile yarn R1,280 Tex/3/3 Glass yarn; Pile weight 1,214 gm/m2.

11. Cut Pile, 1 9.7 stitches/1 0 cm, 5.1 cm total tuft length. Pile yarn R1,280 Tex/3/3 Glass yarn; Pile weight 1,880 gm/m2.

12. Cut Pile, 21.7 stitches/10 cm, 5.1 cm total tuft length. Pile yarn R1,280 Tex/3/3 Glass yarn Pile weight 2,090 gm/m2.

13. Cut pile, 37.3 stitches/10 cms, 5.1 cm loop length. Pile yarn R430 Tex/3 Glass-two ends/needle. Pile weight 2,100 gm/m2.

All the above fabrics were tufted on a machine having a gauge of 12.6 rows per 10 cms.

Examples with different tufting gauges are: 14. Cut Pile, 25.2 rows/l0 cms; 31.5 stitches/10 cm; 3.5 cm loop length. Pile yarn R430 Tex/3 Glass. Pile weight 1,240 gm/m2.

1 5. Loop pile, 31.5 rows/10 cms, 31.5 stitches/1 0 cms 2.5 cm loop length. Pile yarn R430 Tex/3 Glass, Pile weight 1.100 gm/m2.

The fabrics of Examples 1 to 10 and 13 to 15 were all tufted into a primary backing produced by Marglass Limited of Sherbourne, Dorset from glass yarns and referred to by Marglass as Quality ii 7J, loomstate. The fabric construction is understood to be a 4 shaft satin weave with a warp of 189 ends/1 0 cm and 118 picks/1 0 cm weft, both the warp and weft being of 136 Tex glass yarn (Marglass Ref. EC9). The primary backing for Example 11 was Marglass ref. 274, believed to be a plain weave structure with 1 73 ends/10 cm warp and 122 picks/1 0 cm weft, the warp and weft both being of 68 Tex glass yarn (Marglass ref. EC9). Example 12 was tufted into a non-woven primary backing fabric produced by E.

I. Du Pont De Nemours and Company of Delaware, U.S.A. under their Trade -Mark "Typar" believed to be a spun bonded polypropylene fabric of 135 gm/m2. However, any of the backing fabrics could have been used for any of the tufting constructions.

Claims (21)

Claims

1. An exhaust system for an internal combustion engine including an internal surface having a lining to be exposed to exhaust gases emanating from the engine, the said lining including a multiplicity of pieces of yarn (as hereinbefore defined) made from resistant fibres each piece being secured to the surface or to a substrate adjacent thereto and extending away from the surface.

2. An exhaust system as claimed in Claim 1 wherein the pieces of yarn are separate from each other and each is individually secured to the said surface or the substrate.

3. An exhaust system as claimed in Claim 2 wherein each piece of yarn is secured by one end part to the said surface or the substrate.

4. An exhaust system as claimed in Claim 2 wherein each piece of yarn is bent at an intermediate region to define two end portions disposed in a U or V shape and is secured to the said surface or the substrate by its bent intermediate region with its end portions extending away from the surface or substrate.

5. An exhaust system as claimed in Claim 4 wherein the end portions of each piece of yarn are of substantially equal length.

6. An exhaust system as claimed in Claim 4 wherein the end portions of at least some of the pieces of yarn are of unequal length.

7. An exhaust system as claimed in Claim 1 wherein the pieces of yarn are parts of at least one common length of yarn which is formed into loops or folds to define the pieces, portions of the yarn length between the pieces being secured to the said surface or to the substrate at closely spaces points so that the loops or folds extend away from the surface or substrate.

8. An exhaust system as claimed in any of Claims 2 to 7 wherein some of the pieces of yarn are of different lengths.

9. An exhaust system as claimed in any proceding claim wherein the pieces of yarn are secured to the said surface or to the substrate by mechanical locking.

10. An exhaust system as claimed in Claim 9 wherein the pieces of yarn are secured to the said surface or to the substrate by tufting.

11. An exhaust system as claimed in any preceding claim wherein the pieces of yarn are secured to the said surface or to the substrate by bonding.

12. An exhaust system as claimed in any preceding claim wherein at least some of the pieces of yarn include different resistant fibres.

13. An exhaust system as claimed in any preceding claim including pieces of yarn secured to a substrate adjacent to the said internal surface characterised in that the substrate is a fabric produced from resistant fibres as hereinbefore defined.

14. An exhaust system for internal combustion engines including an internal surface having a lining to be exposed to exhaust gases emanating from the engine characterised in that the lining comprises a substrate fabric having a tufted pile of pieces of yarn extending away from the surface, both the substrate fabric and the pieces of yarn being made from resistant fibres as hereinbefore defined.

1 5. An exhaust system as claimed in Claim 14 in which the tufted pile is a loop pile.

16. An exhaust system as claimed in Claim 14 in which the tufted pile is a cut pile.

1 7. An exhaust system as claimed in any of Claims 14 to 16 in which the tufted pile comprises pieces of yarn of different lengths.

18. An exhaust system as claimed in any of Claims 14 to 1 7 in which the substrate of the lining is secured to the said internal surface by bonding.

19. An exhaust system is claimed in any of Claims 14 to 17 in which the substrate of the lining is secured adjacent to the said internal surface by mechanical means.

20. An exhaust system as claimed in Claim 19 in which edges of the substrate are incorporated in seams between parts of the exhaust system.

21. An exhaust system for internal combustion engines including an internal surface having a lining to be exposed to exhaust gases emanating from the engine substantially as hereinbefore described.