JP7242056B2 - Silencers and sound absorbing sheets for internal combustion engines - Google Patents

Description

TECHNICAL FIELD The present invention relates to a muffler for an internal combustion engine and a sound absorbing sheet provided therewith.

A sound absorbing material made of inorganic fibers is disposed between an inner pipe and an outer pipe of a silencer for an internal combustion engine. Conventional sound absorbing materials made of inorganic fibers include those formed by winding a glass wool mat, those formed by molding glass wool into a cylindrical shape, and those formed by stuffing long glass fibers into a bag (Patent Document 1). In addition, the use of glass fiber rovings has also been disclosed (Patent Documents 2 and 3).

JP 2007-170315 A Japanese Patent Application Laid-Open No. 2007-182878 Japanese Patent Publication No. 2013-519037

However, conventional sound absorbing materials made of inorganic fibers have the following problems.
・Inorganic fibers in the muffler were sometimes biased due to the exhaust gas pressure. When the bias occurs, the sound absorption performance tends to deteriorate, and quality fluctuations over a long period of time increase.
・In the work of integrating the inner pipe and the outer pipe by welding, if the inorganic fiber of the sound absorbing material protrudes into the welded part, it causes the welding failure. In addition, it may lead to failure of the welding equipment.
・Inorganic fibers are sometimes mixed with organic matter, but when a large amount of organic matter is included, the organic matter evaporates under the usage environment, causing smoke and odor. It is also not preferable from the viewpoint of adhesion of hydrocarbons and the like.

Accordingly, an object of the present invention is to prevent unevenness of inorganic fibers in a muffler, stably obtain excellent sound absorption performance over a long period of time, and prevent welding defects by eliminating protrusion of inorganic fibers to welded portions. That's what it is. More preferably, it is to reduce the vaporization of the organic matter and prevent the generation of smoke and offensive odors.

The present inventors investigated the use of inorganic fiber rovings and found that bulky inorganic fiber rovings are promising. , it was found that manual repair was required, which easily hindered continuous production. We also investigated the possibility of weaving bulky inorganic fiber rovings into a woven fabric, but found that the restraints between the fibers tended to reduce the sound absorption performance. Based on these, further studies were repeated, and the present invention was achieved.

[1] Sound-absorbing sheet A sound-absorbing sheet provided in a silencer of an internal combustion engine,
Including wefts made of bulky inorganic fiber rovings extending in the sheet width direction and warps extending in the sheet length direction,
At least both ends of the weft in the sheet width direction are woven with the warp to form an end woven cloth portion, and the width of each end woven cloth portion is 1/4 or less of the sheet width,
A sound absorbing sheet characterized in that a part of the weft in the sheet width direction is a non-woven portion that is not woven with the warp.

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(a) Since both ends of the bulky inorganic fiber roving are constrained by the warp yarns of the end woven fabric part, the sound absorbing sheet can be wound around the silencer with less unevenness, and is also resistant to exhaust gas. It has excellent pressure resistance and can prevent unevenness of inorganic fibers even when used for a long time. In addition, bulky inorganic fiber rovings are bulky without being constrained in the non-woven portion, and thus have high sound absorption. As a result, excellent sound absorption performance can be stably obtained over a long period of time.
(b) In addition, since both ends of the inorganic fiber roving are restrained by the warp threads of the end woven fabric, when the sound absorbing sheet is placed on the silencer, the inorganic fiber does not protrude into the welded part, which leads to poor welding. can be prevented.
(c) The edge woven fabric part has no stretchability in the sheet length direction, but the non-woven fabric part has stretchability in the sheet length direction. Therefore, even if there are undulations (diameter difference or curvature) on the outer peripheral surface of the inner pipe, the non-woven colored portion stretches accordingly, so that the sound absorbing sheet can be easily wound around the inner pipe.

Here, both ends of the weft in the sheet width direction are preferably uncut continuous folded ends. This is because fluff of the inorganic fibers is eliminated, and poor welding can be prevented more reliably.
Such a sound absorbing sheet in which both ends of the weft yarn are turned back ends is produced by a shuttle loom that skips the weft yarn by the reciprocating motion of a shuttle, or a shuttleless loom such as a narrow needle loom that does not use a shuttle. It can be manufactured by adjusting the mounting position.
In the case of a narrow needle loom, binder threads can be entwined at both ends in the sheet width direction. Both ends of the sound absorbing sheet can be fixed by heat-sealing the entangled binder threads. When a binder yarn is used, it is desirable to use a yarn made of a polyolefin thermoplastic resin such as polyester, polyethylene, polypropylene, etc., because it emits less harmful gas when heated. The strength of the ends can be reinforced by entangling metal threads instead of binder threads. In this case, the metallic thread is preferably made of a heat-resistant alloy such as stainless steel or an iron-chromium alloy.

The following aspects (a), (b), and (c) are included for the middle of the weft in the sheet width direction.
(a) A mode in which the middle portion of the weft yarn in the sheet width direction is woven with the warp yarn to form an intermediate woven cloth portion, and the width of the intermediate woven cloth portion is ⅓ or less of the width of the sheet.
It is possible to more reliably prevent the unevenness of the inorganic fibers when arranging and using the silencer.
It is preferable that the intermediate woven fabric portion is located at the center of the weft in the sheet width direction. This is because the sound absorbing sheet can be easily folded at the intermediate woven fabric portion.
In addition, the intermediate woven fabric portion has no extensibility in the sheet length direction, and reduces the extensibility of the non-woven portion. However, if the outer peripheral surface of the inner pipe has no or little undulations, it can be applied without any problem.

(b) A mode in which an intermediate sewn portion sewn in the seat length direction with a sewing thread is formed in a part of the weft in the middle in the seat width direction.
When the sewing thread is melted, the inorganic fibers are more reliably prevented from being unbalanced during placement on the muffler, and when the sewing thread is not melted, during placement on the muffler and during use.
The intermediate sewn portion is preferably located in the center of the weft in the sheet width direction. This is because the sound absorbing sheet can be easily folded at the intermediate sewn portion.
Note that the intermediate sewn portion may be either non-stretchable in the seat length direction or stretchable in the seat length direction due to stretchable sewing thread and/or stretchable seams, as will be described later. be.

(c) A mode in which the middle of the weft yarn in the sheet width direction is entirely a non-woven portion. That is, neither an intermediate woven fabric portion nor an intermediate woven fabric portion is formed in the middle.
Also in this aspect, it is possible to prevent the unevenness of the inorganic fibers to a certain extent or more during the arrangement and use of the silencer.
And it can be applied even when the outer peripheral surface of the inner pipe has large undulations.

The inorganic fiber roving preferably contains 1.5% by mass or less of a sizing agent and does not contain other organic matter. This is because very little exhaust gas is generated during heating.

[2] Silencer for internal combustion engine An inner pipe, an outer pipe, and the sound absorbing sheet according to any one of claims 1 to 8 arranged in a winding shape between the inner pipe and the outer pipe. and wherein both ends of the outer pipe are welded to the inner pipe.

The sound absorbing sheet may be folded to increase its thickness, and then arranged in a coiled shape.

Another functional member may be interposed between the sound absorbing sheet and the inner pipe.

According to the present invention, the inorganic fibers are less likely to be biased in the muffler, and excellent sound absorption performance can be stably obtained over a long period of time. can.

FIG. 1 is a front view of a sound absorbing sheet of Example 1. FIG. FIG. 2(a) is a schematic view of the sound absorbing sheet folded in the sheet length direction, and FIG. 2(b) is a schematic view of the sound absorbing sheet folded in the sheet width direction. FIG. 3(a) is a partially broken front view of a silencer provided with the same sound absorbing sheet, and FIG. 3(b) is a partially broken front view of the silencer provided with the same sound absorbing sheet and metal fibers. FIG. 4 is a front view of the sound absorbing sheet of Example 2. FIG. FIG. 5 is a schematic diagram showing another example of the seams of the intermediate sewn portion of the sound absorbing sheet. FIG. 6 is a front view of the sound absorbing sheet of Example 3. FIG.

[1] Weft yarn (inorganic fiber roving)
Examples of inorganic fibers include, but are not limited to, glass fibers, basalt fibers, silica fibers, rock wool, alumina fibers, ceramic fibers, etc. Glass fibers are preferred because they are inexpensive and versatile.
The roving count is not particularly limited, but is preferably 200 to 9600 TEX, more preferably 1200 to 7000 TEX.
The fiber diameter of the roving is not particularly limited, but is preferably 9-30 μm, more preferably 12-24 μm.
Bulky inorganic fiber rovings are obtained by opening the fibers by air blowing or the like. The bulky material preferably has a bulkiness with a shrinkage rate of 1 to 10% in the length direction, and more preferably a bulkiness with a shrinkage rate of 3 to 7% in terms of sound absorption performance and fiber scattering prevention. The compression ratio can be adjusted pneumatically.

[2] Warp Although the warp is not particularly limited, rovings made of fiber filaments, spun yarns, twisted yarns, and the like can be exemplified. Rovings are preferable, and inorganic fiber rovings are more preferable.
The number of rovings is not particularly limited, but is preferably 200 to 9600 TEX, more preferably 1200 to 7000 TEX.
The fiber diameter for roving is not particularly limited, but is preferably 9 to 30 μm, more preferably 12 to 24 μm.
The warp fibers are not particularly limited, but inorganic fibers, metal fibers, organic fibers and the like can be exemplified, and inorganic fibers are preferred.
Examples of the inorganic fiber include, but are not limited to, glass fiber, basalt fiber, silica fiber, rock wool, alumina fiber, and ceramic fiber. Glass fiber is preferred because it is inexpensive and versatile.
Examples of organic fibers include, but are not limited to, natural materials such as polyester, polypropylene, polyethylene, nylon, aramid, and cotton, synthetic rubber, and fibers made of carbon.

[3] Edge woven fabric part The weaving method of the edge woven fabric part is not particularly limited, but a plain weave is preferable in terms of workability.
The width of each end woven cloth portion can be determined by the thickness, number and pitch of the warp yarns.
The width of each end woven fabric portion is preferably 1/100 to 1/4 of the sheet width, more preferably 1/6 or less, and most preferably 1/8 or less. If the width of each end woven cloth portion is too small, the binding property of both ends of the weft yarn is reduced, and if the width of each end woven cloth portion is too large, the width of the non-woven portion is reduced and the sound absorption is reduced.
The width of each end woven cloth portion is preferably 2 to 50 mm, more preferably 10 to 30 mm.
The thread density is not particularly limited, but is preferably 1 to 24, more preferably 2 to 14, per 25 mm regardless of warp or weft.
The mass of each end cloth portion is not particularly limited, but is preferably 300 to 4000 g/m ² , more preferably 600 to 2400 g/m ² .
The center-to-center distance between the end woven fabric portions at both ends when there is no central woven fabric portion is not particularly limited, but is preferably 25 to 250 mm, more preferably 50 to 150 mm.

[4] Intermediate woven cloth portion As described above, the intermediate woven cloth portion is preferably located at the center of the weft in the sheet width direction, but may be located at a location other than the center, and the number may be one or more. .
The weaving method of the intermediate woven cloth portion is not particularly limited, but a plain weave is preferable in terms of workability.
The width of the intermediate woven cloth portion can be determined by the thickness, number and pitch of the warp yarns.
The width of the intermediate woven fabric portion is preferably 1/50 to 1/3 of the sheet width, more preferably 1/4 or less, and most preferably 1/5 or less.
The width of the intermediate woven fabric portion is preferably 2 to 100 mm, more preferably 10 to 40 mm, in numerical terms.
The thread density is not particularly limited, but is preferably 1 to 24, more preferably 2 to 14, per 25 mm regardless of warp or weft.
The mass of the middle edge cloth portion is not particularly limited, but is preferably 300 to 4000 g/m ² , more preferably 600 to 2400 g/m ² .
The center-to-center distance between the central woven cloth portion and each end woven cloth portion and the center-to-center distance between the central woven cloth portions are not particularly limited, but are preferably 25 to 250 mm, more preferably 50 to 150 mm.

[5] Sewing Thread Sewing thread is not particularly limited, but spun yarn, twisted yarn and the like can be exemplified.
The fibers of the spun yarn are not particularly limited, but inorganic fibers, metal fibers, organic fibers and the like can be exemplified. Inorganic fibers are particularly preferred.
Inorganic fiber yarns are not stretchable, but are suitable when stretchability is unnecessary or when forming seams with high stretchability, as will be described later.
Sewing threads with high elongation include Ace Crown (trade name) and Hyper (trade name) manufactured by Ace Crown, Eiffel sewing thread (trade name: #30, #50) and Leona (trade name: #50) manufactured by Kanagawa, and Fujix (trade name). Organic fiber yarns such as Woolly yarn and Resilon (245dTEX #50) manufactured by Asahi Kasei Leona Co., Ltd., under the trade name of Woolly, and Unilon (#50) manufactured by Asahi Kasei Leona.

[6] Intermediate sewn part If the outer peripheral surface of the inner pipe has no or small undulations, the intermediate sewn part does not need elasticity, so the intermediate sewn part can be sewn with a general sewing thread and a general straight line. .
However, if there are large undulations on the outer peripheral surface of the inner pipe, the intermediate sewn part also needs to be stretchable in order to improve compliance. It is preferable to
Extensible sewing threads are exemplified above.
Examples of highly extensible stitches include (a) elastic stitches, (b) zigzag stitches, (c) half reverse stitches, and (d) dotted line zigzag stitches shown in FIG.

[7] Silencer The sound absorbing sheet may be wound once, or may be wound multiple times to increase the thickness. Alternatively, the sheet may be folded in the longitudinal direction as shown in FIG. 2(a) or folded in the sheet width direction as shown in FIG. 2(b) to increase the thickness before winding. . When folded in the sheet width direction, it is preferable to weave in the intermediate woven fabric portion.
As shown by the arrows in FIGS. 1 and 2, the sound absorbing sheet is basically wound so that the width direction of the sheet (the direction in which the wefts extend) forms a circumference. However, it is also possible to wind the sheet so that the longitudinal direction of the sheet (the direction in which the warp threads extend) forms a circumference.

As another functional member interposed between the sound absorbing sheet and the inner pipe, metal wool such as stainless steel wool, metal foil, metal mesh, knit made of glass fiber, or the like formed into a sleeve can be exemplified.

Next, embodiments of the present invention will be described with reference to the drawings. Note that the structures, shapes, dimensions, materials, numerical values, etc. described in the examples are examples, and can be changed as appropriate without departing from the gist of the invention.

[Example 1]

FIG. 1 shows the sound absorbing sheet 1 of Example 1, FIG. 2 shows an example of folding the sound absorbing sheet 1, and FIG.

The sound absorbing sheet 1 includes weft yarns 2 made of bulky inorganic fiber rovings extending in the sheet width direction, and warp yarns 3 made of inorganic fiber rovings extending in the sheet length direction. All of the inorganic fiber rovings contained 1.5% by mass or less of sizing agent and contained no other organic matter.

Both ends of the weft yarn 2 in the sheet width direction are woven together with the warp yarn 3 to form an end woven cloth portion 4, and the width w1 of each end woven cloth portion 4 is, for example, 1/50 to 1/ of the sheet width W. 10.
A portion of the weft yarn 2 in the middle in the sheet width direction (central portion in this example) is woven with the warp yarn 3 to form an intermediate woven cloth portion 5, and the width w2 of the intermediate woven cloth portion 5 is, for example, the width of the seat. It is 1/20 to 1/5 of W.
A portion of the weft yarn 2 in the sheet width direction (in this example, a portion between each end woven cloth portion 4 and the intermediate woven cloth portion 5) is a non-woven portion 6 that is not woven with the warp yarn 3. As shown in FIG.
Both ends of the weft 2 in the sheet width direction are uncut continuous folded ends 7 .

A muffler 10 shown in FIG. 3( a ) includes an inner pipe 11 , an outer pipe 12 , and a sound absorbing sheet 1 wound between the inner pipe 11 and the outer pipe 12 . It is.
The muffler 10 shown in FIG. 3B includes an inner pipe 11, an outer pipe 12, a metal fiber 14 such as stainless wool wound between the inner pipe 11 and the outer pipe 12, and a sound absorbing material. The seat 1 is included.

A plurality of through holes are formed in the inner pipe 11 . The inner pipe 11 of this example has no undulations on the outer peripheral surface, and the sound absorbing sheet does not need to be stretchable.
The sound absorbing sheet 1 is folded in the sheet width direction to increase its thickness, and then wound so as to form a circumference in the sheet width direction (the direction in which weft threads extend).
Both ends of the outer pipe 12 are joined to the inner pipe 11 at welded portions 13 .

[Example 2]
The sound absorbing sheet 1 of Example 2 shown in FIG. It is different from the first embodiment in that a split intermediate sewn portion 16 is formed, and the rest is the same as the first embodiment.
The intermediate sewn part 16 is straight-stitched with a general sewing thread 15 with low stretchability, but it is possible to use a sewing thread with high stretchability or make a seam with high stretchability (Fig. 5). can also
The sound absorbing sheet 1 of the second embodiment can also be arranged in the muffler 10 in the same manner as in the first embodiment.

[Example 3]
A sound absorbing sheet 1 of Example 3 shown in FIG.
The sound absorbing sheet 1 of the third embodiment can also be arranged in the muffler 10 in the same manner as in the first embodiment.

According to these Examples 1, 2, and 3, the inorganic fibers are less likely to be biased in the silencer 10, and excellent sound absorption performance can be stably obtained over a long period of time. Welding defects can be prevented without

It should be noted that the present invention is not limited to the above-described embodiments, and can be embodied with appropriate modifications without departing from the gist of the invention.

REFERENCE SIGNS LIST 1 sound absorbing sheet 2 weft 3 warp 4 end woven fabric part 5 intermediate woven fabric part 6 non-woven part 7 folded end 10 muffler 11 inner pipe 12 outer pipe 13 welded part 14 metal fiber 15 sewing thread 16 intermediate sewn part

Claims (12)

A sound absorbing sheet (1) disposed in a silencer (10) of an internal combustion engine,
Including weft yarns (2) made of bulky inorganic fiber rovings extending in the sheet width direction and warp yarns (3) extending in the sheet length direction,
At least both ends of the weft (2) in the width direction of the sheet are woven with the warp (3) to form the end woven cloth portion (4), and the width (w1) of each end woven cloth portion (4) is the width of the sheet. 1/4 or less of the width (W),
A sound absorbing sheet characterized in that a part of the weft (2) in the sheet width direction is a non-woven portion (6) that is not woven with the warp (3). 2. The sound absorbing sheet according to claim 1, wherein both ends of the weft (2) in the sheet width direction are uncut continuous folded ends (7). A middle portion of the weft (2) in the sheet width direction is woven with the warp (3) to form an intermediate woven cloth portion (5), and the width of the intermediate woven cloth portion (5) is 1 of the width of the sheet. /3 or less, the sound absorbing sheet according to claim 1 or 2. 4. The sound absorbing sheet according to claim 3, wherein the intermediate woven fabric portion (5) is located at the center of the weft (2) in the sheet width direction. 3. The sound absorbing sheet according to claim 1 or 2, wherein an intermediate sewn portion (15) sewn in the longitudinal direction with a sewing thread is formed in a portion of the weft (2) in the middle in the seat width direction. 6. The sound absorbing sheet according to claim 5, wherein the intermediate sewn portion (15) is located at the center of the weft (2) in the sheet width direction. 7. The sound absorbing sheet according to claim 5 or 6, wherein the intermediate sewn part (15) is sewn with stretchable sewing thread. 8. The sound absorbing sheet according to claim 5, 6 or 7, wherein the intermediate seams (15) are sewn with stretch seams. 3. The sound absorbing sheet according to claim 1 or 2, wherein the middle portion of the weft yarns (2) in the sheet width direction is a non-woven portion (6). 10. The sound absorbing sheet according to any one of claims 1 to 9, wherein the inorganic fiber roving has 1.5% by mass or less of sizing agent adhering thereto and does not contain other organic matter. 11. The inner pipe (11), the outer pipe (12), and the inner pipe (11) and the outer pipe (12) arranged in a coiled manner according to any one of claims 1 to 10. A muffler for an internal combustion engine, comprising a sound absorbing sheet (1), wherein both ends of an outer pipe (12) are welded to an inner pipe (11). 12. The muffler for an internal combustion engine according to claim 11, wherein the sound absorbing sheet (1) is folded to increase its thickness and arranged in a winding shape.

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