JPS61185611A - Exhaust muffler for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent breakage of a metal foil provided on an outer circumference of an apertured pipe having a plurality of apertures, by fixing the metal foil and a sound absorbing material provided on the outer circumference of the pipe through the metal foil by means of a holding band, and forming the apertures of the pipe at a part except an opposite part to the holding band. CONSTITUTION:A cylindrical porous sound absorbing material 8 is provided on an outer circumference of an apertured pipe 6 having a plurality of apertures 6a through a metal foil 7. The sound absorbing material 8 and the metal foil 7 are fixedly fastened by a holding band 9. The apertures 6a of the apertured pipe 6 are formed at a part except an opposite part to the holding band 9. Thus, even if the holding band 9 is strongly fastened, the metal foil located at the opposite part to the holding band is prevented from being broken by the apertures.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an exhaust silencing device for an internal combustion engine that uses a sound absorbing material.

[Conventional technology]

rt as an exhaust silencer for internal combustion engines using sound-absorbing materials
As shown in Japanese Unexamined Patent Publication No. 58-206817, a cylindrical porous sound absorber is disposed on the outer periphery of a perforated nozzle 1 through which exhaust gas flows, with a metal thin film interposed therebetween, and a vacant chamber is further provided on the outer periphery. A porous sound absorber absorbs and attenuates exhaust noise propagating from the perforated pipe to the empty space through the perforated thin film.

[Problem that the invention seeks to solve]

By the way, this type of muffler is not suitable for high temperatures of internal combustion engines (88
In addition to requiring heat resistance against exhaust gas (approximately 00°C), it also requires a strong structure that can withstand large vibrations. While the countermeasures for the holding structure are non-luminous and are used as a silencer for internal combustion engines, it is still impractical @
Contains.

For this reason, it is conceivable to use a band as a holding structure to hold the porous acoustic material on the perforated knob, but if this band is sufficiently tightened, the porous sound absorbing material will be It is compressed and deformed by the force, and is deformed so that it is pushed out through the hole of the perforated pipe. At the same time, the metal thin film between the sound absorbing material and the perforated pipe protruding from the hole is pushed out of the hole, and the metal thin film is damaged at the hole of the perforated pipe facing the punt, and the sound absorbing material for exhaust noise is forced out. There are problems such as a reduction in the propagation function of the exhaust gas, a reduction in the ability to prevent exhaust gas from adhering to the sound absorbing material, and further damage to other parts of the metal thin film.

[Means for solving problems]

In the present invention, the outer periphery of the sound absorbing material placed on the outer periphery of the perforated pipe is secured by a holding band [i! Adding i1, the large number of holes in the perforated pipe are formed in the shape of ``C'' in the portion excluding the portion facing the holding band.

[For production]

The function of the holding band according to the present invention is to hold the sound absorbing material together with the metal thin film in a fixed position on the perforated pipe even under severe conditions during the exhaust of an internal combustion engine, thereby preventing damage to the metal thin film due to movement between them. By forming the hole on the V2VC perforated pipe except for the part facing the holding band, the metal thin film is prevented from being damaged even by shrinkage deformation of the sound absorbing material due to the tightening of the band.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 4.
First, in Figure @1, (1) is a cylindrical outer case with a bottom to form an expansion block for the exhaust gas passage of the engine, and its inner chamber is formed by two partition walls t2) and +31. Three vacancies (A), CB), (c) I
It is sectioned C. (4) rtFrom one end side of the above case (1), pass each wall 12), +3) straight through °C vacant room (
C) is an exhaust gas inflow pipe opened to r5)ri, a communication pipe that allows exhaust gas to flow from the above-mentioned cavity (C) to the above-mentioned cavity (A), and (6) is an exhaust gas inflow pipe that has flowed into the above-mentioned cavity (A). To discharge the above and each wall +2), +3) f:
It is a perforated pipe on the outflow side that penetrates and protrudes to the other end side of the case (1), and the core perforation pipe is a stainless steel cylindrical pipe with a large number of holes ( 6a) (hole diameter 2 cages, open area ratio about 40) was carved and dried at °C. (7) is a commercially available Ni-Cr metal thin film with a thickness of 10 μm, and (8) is a cylindrical shape placed over the hole (6a) forming part of the perforated pipe (6) with this metal thin film sandwiched therebetween. This porous sound absorber is made by molding into a cylindrical shape a Ni-Cr spongy porous metal flat plate (trade name: Celmet) manufactured by Sumitomo Electric, which is already commercially available. As can be seen in Figures 2 to 4, the case is divided into two in the circumferential direction, and the perforated pipe (6)
A notch (8a) is formed so that a portion of the large number of holes is directly exposed to the cavity (B). In addition, the above metal thin film (7)
ri The porous sound absorber (6) is constructed in the same shape so as to cover the entire inner circumferential surface of the porous sound absorber (6). (9) is a tightening band that is tightened at predetermined points (two places) on the outer periphery of the porous sound absorbing body (6) and held on the perforated pipe (6);
A metal band having a predetermined width (approximately 2 on) is formed into an annular shape, and a portion thereof has a VC dimension adjustment portion (9a). Here, a large number of holes (6a) formed in the perforated pipe (6) are connected to the tightening band (9) in the perforated pipe (6).
It is not formed in the part (6b) opposite to this part (6b
) (see Figures 1 and 3).

Next, the operation of the device configured in this manner will be explained.

Engine exhaust gas flows through the inflow pipe (4) as shown by the arrow in Figure 1 →
It circulates through the path of empty room (C) → communication pipe (5) → empty room (4) → perforated pipe (6). At this time, each pipe 14)
, (expansion due to volume change between 51 and empty room (Q, prisoner),
The porous sound absorber (8) provides a predetermined sound silencing effect due to the contraction, and further prevents the exhaust sound from propagating from the numerous holes (6a) in the perforated pipe (6) into the empty room through the thin film (7).
In addition, in the notch (8a) of the porous sound absorber (8), the hole (6a) directly communicates with the cavity (B) K to provide a sound deadening effect through the combined use of a type of resonance device, Exhaust noise is muffled.

Here, a porous sound absorber (
The porous sound absorber (8) is held tightly against the perforated pipe (6) by the tightening band (9), so that even under severe conditions during engine exhaust, the porous sound absorber (8) remains intact together with the metal thin film (7).
) It is possible to prevent the metal thin film (7) from being damaged due to movement between them by holding it at a fixed position on the fully open pipe, and it is possible to maintain the desired sound-dampening performance over a long period of time.

Also, since the large number of holes (6a) #: of the perforated pipe (6) are formed except for the part (6b) where the tightening band (9) is arranged, the tightening band (9) can be made stronger. Even if it is tightened, the porous sound absorber (8) at that part will not be extruded into the hole (6a) together with the metal thin film (7) due to compressive deformation, and therefore the metal thin film (7) will not be extruded into the hole (6a) due to this extrusion deformation i.
), thereby making it possible to construct a device that is sufficiently strong and free from damage to the metal thin film. [Effects of the Invention] As described above, according to the present invention, the holding band Since the porous sound absorber can be firmly held together with the metal thin film on the perforated pipe and their movement can be prevented, damage to the metal thin film due to the movement can be prevented.

Since the many holes of the perforated pipe are formed except for the opposing parts of the holding band, even if the holding band is firmly tightened, the metal thin film in the band part can be prevented from being damaged by the holes. It is possible to maintain the silencing performance in °C over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIGS. 2, 3, and 4 are a perspective view, a front view, and a side view of the main parts of FIG. 1. In the figure, (C) is empty, (6) i-j
A perforated pipe, (6a) an RJ hole, (6b) a portion facing the t-t band, (7) a metal thin film, (8) a porous sound absorber, and (9) a tightening band. In addition, the same parts are indicated by the same reference numerals in the figures.

Claims (1)

[Claims] A perforated pipe with a large number of holes through which exhaust gas from an internal combustion engine flows, a cylindrical porous sound absorber disposed on the outer periphery of the perforated pipe with a thin metal film interposed therebetween, and an outer periphery of the porous sound absorber. and a holding band for holding the porous sound absorber together with the metal thin film around the outer periphery of the perforated pipe, the large number of holes formed in the perforated pipe having at least An exhaust muffling device for an internal combustion engine, characterized in that it is formed excluding a portion facing the holding band.