JP3146136B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a muffler which is mounted on an exhaust pipe of an automobile, a motorcycle or the like and absorbs noise generated when exhaust gas is emitted.

[0002]

2. Description of the Related Art Conventionally, a silencer of this type having a structure shown in FIG. 4 is known. In FIG. 4, reference numeral 1 denotes a porous tube having a large number of air holes, 2 denotes a mat-shaped sound absorbing material such as rock wool or glass fiber wound around the tube, 3 denotes an outer cylinder that covers the outer periphery of the mat-shaped sound absorbing material, Is a cap, 6 is a seal material such as SUS mesh, 7 is an exhaust pipe connected to the cap by welding or the like, and caps 4 and 5 are connected to the exhaust pipe 7 and the outer cylinder 3 by welding portions a, b, c, and d. It is a slide mechanism in which the sealing material 6 is provided between the perforated pipe 1 and the cap 5 by welding, and absorbs thermal expansion and contraction of the perforated pipe. The silencer having this configuration functions as a silencer by absorbing noise generated when exhaust gas is emitted by the mat-shaped sound absorbing material 2 that covers the ventilation holes of the perforated pipe 1.

[0003]

The following problems have been pointed out with the silencer having the above-mentioned structure. (1) The perforated pipe is usually made of punched metal, and the number and size of the holes are limited in terms of strength.
The ratio of the open area of the holes, that is, the opening ratio cannot be increased, and the area where the sound absorbing material is blocked from the exhaust gas as the sound source increases, thereby limiting the sound absorbing effect. (2) When both ends of the perforated tube are welded to the cap, thermal stress (due to expansion and contraction due to high-temperature exhaust gas) is generated in the perforated tube, and the thermal stress causes a crack to be generated and the tube is easily broken. Therefore, as shown in FIG.
Is not welded to the perforated tube, and S
The sealing material 6 such as a US mesh is loaded, and the expansion
It forms a slide mechanism that can tolerate contraction, but this slide mechanism not only requires time and effort in its configuration,
The sealing material is easy to fall off. (3) To prevent fibers of the sound absorbing material wound around the outer periphery of the perforated tube from scattering out of the holes of the perforated tube, wrap a SUS wool mat around the outer periphery of the perforated tube, and wrap the SUS wool mat so that it does not come off. Means of spot welding at several places to prevent the scattering of the fiber of the sound absorbing material from the air holes of the perforated pipe have been proposed and put to practical use. However, when the SUS wool mat is wound around the perforated pipe, the SUS fiber breaks. And fall, SUS
There is a problem in safety, such as the fibers sticking into the hands of workers.
In addition, the use of the scattering prevention material increases the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems at a time, and has a large aperture ratio, a small area in which a sound absorbing material is shielded from exhaust gas as a sound source, and a low sound absorbing effect. It is a main object of the present invention to provide a silencer capable of effectively preventing scattering of fibers of a sound absorbing material, which does not require a good slide mechanism capable of permitting thermal expansion and contraction.

[0005]

Means for Solving the Problems The present invention, on the inner peripheral side of the metal coil-shaped spring, to fitted a sleeve made of inorganic lengthy fibers
And both ends are folded back to the outer periphery of the coil spring
A mat-shaped sound absorbing material layer made of inorganic fiber was provided on the outer peripheral side of the coil-shaped spring, and the outside of the mat-shaped sound absorbing material layer was covered with an outer cylinder, and both side surfaces of the outer cylinder were covered with caps. The gist is that.

[0006] The metal coil spring is to replace a conventional perforated tube, and the whole is kept in the form of a tube member, and the opening ratio (of the wire material of the entire peripheral surface including the wire material of the coil spring). To adjust the ratio of the part without
It is configured by appropriately selecting the thickness of the metal wire used and the winding coil pitch.

[0007] As the inorganic long fibers forming the sleeve, it is preferable to use heat-resistant inorganic long fibers such as glass fibers, silica fibers, and alumina fibers. In particular, since these fibers are obtained as long fibers, they are advantageous for knitting. The inorganic long fiber sleeve may have two to three layers as necessary.

[0008] The mat-shaped sound absorbing material may have either a structure in which the mat-shaped sound absorbing material is formed into a laminated shape by being wound up or a structure in which the mat-shaped sound absorbing material is formed in a concentrically laminated shape. Examples of the sound absorbing material include not only rock wool and glass fiber but also silica fiber and ceramic fiber.

In the silencer having the above-described structure, the aperture ratio of the coil spring is much larger than that of the conventional perforated tube.
The area where the sound absorbing material is blocked from the exhaust gas as the sound source is reduced, and the sound absorbing effect is improved. As the sleeve,
A sleeve obtained by sewing a woven fabric made of inorganic long fibers into a tubular shape, a sleeve made by knitting the same fibers, and the like can be used, but a sleeve made by knitting inorganic long fibers is preferably used. . Since the sleeve made by knitting has elasticity, the end of the sleeve inserted into the inner peripheral side of the coil spring can be easily folded back to the outer peripheral side. The holding force can be enhanced and the sleeve can be prevented from being displaced when the exhaust pipe is fitted. In addition, since it can be directly knitted into a tubular shape at the time of knitting, there is an advantage that the step of processing into a tubular shape can be omitted. The sleeve functions to prevent scattering of the fibers of the sound absorbing material. Further, the sleeve is knitted or woven by changing the diameter and number of yarns to be adjusted to an appropriate stitch or an interval between the stitches, so that the ventilation resistance of the sleeve can be adjusted to an appropriate range that does not adversely affect the sound absorbing performance.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 to 3, a sleeve made of inorganic long fiber is provided on the inner peripheral side of a coil spring 8 made of metal.
The outer peripheral side of the coil-shaped spring both ends thereof as well as fitted to 9
The coil-shaped spring 8 is wound around the mat-shaped sound absorbing material 2, the outer cylinder 3 is provided on the outer periphery thereof, and the end surface of the sound absorbing material 2 is covered with caps 4 and 5. The openings at both ends of the sleeve 9 fitted on the inner peripheral side of the coil spring 8 are used as fitting parts of the exhaust pipe 7.

[0011]

1 to 3 show an embodiment of the present invention. The same or similar members as those in FIG. 4 are denoted by the same reference numerals. In the figure, reference numeral 8 denotes a coil-shaped spring in which a metal wire having a required thickness is formed into a coil at a required pitch, and a sleeve 9 having a required length knitted with inorganic long fibers is inserted into an inner peripheral side thereof. A sleeve portion where the sleeve 9 protrudes from both ends of the coil-shaped spring 8 is folded back to the outer peripheral side of the spring to form a folded portion 9a. On the outer peripheral side of the coil-shaped spring 8, a mat-shaped sound absorbing material 2 made of an inorganic fiber is provided.
And the outside is covered with the outer cylinder 3, and both side surfaces of the outer cylinder 3 are covered with caps 4 and 5. Openings at both ends of the sleeve 9 fitted on the inner peripheral side of the coil spring 8 are used as fitting portions of the exhaust pipes 7, and the caps 4, 5 are welded to the exhaust pipes 7, 7. Welded at d.

[0012] In the silencer having the above-described structure, the coil-shaped spring has a greatly increased aperture ratio as compared with a conventional perforated tube, and the sound absorbing effect is improved. Further, since the coil-shaped spring 8 absorbs thermal expansion and contraction at that portion, there is no need to provide a slide mechanism for absorbing thermal expansion and contraction unlike a conventional porous tube. On the other hand, the knitting sleeve 9 made of inorganic long fibers inserted on the inner peripheral side of the coil spring 8 plays a role of preventing the fibers of the sound absorbing material 2 from scattering. By changing the diameter and the number of knitting yarns, the sleeve can be adjusted to an appropriate weave interval, and the airflow resistance of the sleeve can be adjusted to an appropriate range that does not adversely affect the sound absorbing performance. In addition, the knitted sleeve 9
As shown in the figure, since both ends can be easily folded back to the outer peripheral side of the coil spring 8, the folded portion 9a enhances the holding force of the sleeve to the coil spring, and
This can help prevent the sleeve from shifting when the exhaust pipe is fitted.

[0013]

As described above, according to the structure of the muffler according to the present invention, the following effects can be obtained. (1) Since a coiled spring is used in place of the conventional perforated tube, the aperture ratio can be greatly increased, and the sound absorbing effect can be significantly improved. (2) By increasing the sound absorbing effect, the size of the silencer itself can be reduced, and the size and weight can be reduced. (3) The use of the coil-type spring absorbs thermal stress, prevents breakage as occurs in a conventional perforated tube, and eliminates the need for a troublesome slide mechanism. (4) By using a sleeve knitted with inorganic long fibers inside the sound absorbing material, scattering of the fibers of the sound absorbing material is prevented, and the sound absorbing material and the coil-shaped spring are protected from the heat of exhaust gas. (5) Place both ends of the sleeve on the outer periphery of the coil spring
The sleeve is folded back to form a folded part,
The holding force of the il-shaped spring is enhanced and the
This can help prevent sleeve displacement.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a muffler showing one embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a side view of a state in which a knitting sleeve is inserted into a coil spring.

FIG. 4 is a longitudinal sectional view of a conventional silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Perforated pipe 2 Mat-shaped sound absorbing material 3 Outer cylinder 4, 5 Cap 6 Sealing material 7 Exhaust pipe 8 Coil spring 9 Sleeve 9a Sleeve turn-back part

Continued on the front page (56) References Japanese Utility Model Sho 58-62114 (JP, U) Japanese Utility Model Sho 61-59819 (JP, U) Japanese Utility Model Hei 4-71234 (JP, U) (58) Fields surveyed (Int) .Cl. ⁷ , DB name) F01N 1/24

Claims (1)

(57) [Claims] 1. A on the inner peripheral side of the metal coiled spring, carp opposite ends thereof as well as fitted a sleeve made of inorganic lengthy fibers
The coil-shaped spring is provided with a mat-shaped sound absorbing material layer made of inorganic fibers, and the outer side of the mat-shaped sound absorbing material layer is covered with an outer cylinder. A silencer characterized by covering both sides with caps.