JPH076377B2 - Silencer for internal combustion engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a silencer provided in an exhaust pipe of an internal combustion engine.

[Prior Art] One of conventional silencers has a large number of ventilation holes penetrating a part of an exhaust pipe and surrounds a part of the exhaust pipe with general glass wool as a sound absorbing material. There is something.

However, since the high-temperature exhaust gas that passes through the exhaust pipe of the internal combustion engine at high speed exerts a pulsating wave on the glass wool directly through the vent hole, the glass wool gradually deteriorates and is divided into short pieces. There was a problem that the sound absorbing effect was sucked and scattered to the outside air, and the muffling effect gradually decreased with this.

In particular, recently, as the output of an internal combustion engine is increased, it is required to improve the sound absorption coefficient of a muffler, and therefore the hole diameter of the ventilation hole is increased or the arrangement interval is decreased, so that the glass wool is scattered. There was a tendency to increase more.

Therefore, as shown in FIG. 6, a metal fiber cotton body 23 made of stainless steel fiber is first wrapped around the outer circumference of the exhaust pipe 22,
Next, as shown in FIG. 7, the outer circumference of which is covered with a glass wool molding pipe 24, or the same exhaust material is wound around the outer circumference of the exhaust pipe 22, and a linear glass wool 25 is wound around the outer circumference. A material that prevents deterioration and scattering of the glass wool 25 by the metal fiber cotton 23 has been developed, such as a material that is wound and wound with a string 26 and stopped. Also, instead of the string 26, there is also one in which an adhesive is applied to the surface of the glass wool and the glass wool is wound in a double layer and stopped.

[Problems to be Solved by the Invention] However, in the metal fiber cotton-like material 23, the metal fibers are arranged two-dimensionally and are not three-dimensionally entangled, and
Unless it is pressed down, the density is low. Therefore, when used, the effect of stopping the scattering of glass wool was weak. Further, when winding the exhaust pipe 22, it is necessary to hold down the fluffy metal fiber cotton body 23, which makes the work difficult.

In addition, the type of covering the glass wool molding pipe 24 is such that when the outer tube 27 is covered, it is between the inner peripheral surface of the outer tube 27 and the outer peripheral surface of the glass wool molding pipe 24, or the inner circumference of the outer tube 27. A gap may be formed between the end face and both end faces of the glass wool molded pipe 24, and this gap may cause abnormal noise.

Further, the type in which the cotton-like glass wool 25 is wound and stopped with the string 26 is not easy to wind and the productivity is poor, and the outer peripheral surface of the glass wool 25 is a part where the string 26 is wound. Since there is a difference in height between the non-wound portion and the non-wound portion, a gap is generated between the outer peripheral portion of the outer tube 27 and the inner peripheral surface of the outer tube 27, which may cause abnormal noise.

Further, in a type in which glass wool coated with an adhesive is wound in a double layer and then stopped, it takes time to dry the adhesive and productivity is poor.

An object of the present invention is to provide a novel silencer for an internal combustion engine, which prevents deterioration and scattering of glass wool, does not reduce the silencing effect of the silencer, has good productivity, and prevents abnormal noise during use. To do.

[Means for Solving the Problems] In order to achieve the above object, a silencer for an internal combustion engine according to a first aspect of the present invention is an exhaust pipe in which a large number of ventilation holes are partially formed, glass wool, and a metal fiber cotton-like material. A composite mat in which glass fibers of glass wool and metal fibers of cotton-like material are intertwined by overlapping the body and needle punching at the same time,
A structure including a sound deadening layer formed by winding a metal fiber cotton-like material on the outer circumference of a part of the exhaust pipe so as to be the inner side, and an outer pipe covering the outer peripheral surface and both end surfaces of the sound deadening layer. did.

A silencer for an internal combustion engine according to claim is formed by needle-punching an exhaust pipe in which a large number of vent holes are partially formed, and a metal fiber cotton-like material, and is formed on the outer periphery of a part of the exhaust pipe. A sound deadening layer made of a wound metal fiber mat and a glass wool wound around the outer circumference of the metal fiber mat, and an outer tube covering the outer peripheral surface and both end surfaces of the sound deadening layer.

The silencer for an internal combustion engine according to claim 3 is the silencer according to claim 1 or 2 above.
In the muffler, the edge of the metal fiber cotton-like body of the muffling layer is fixed to the exhaust pipe.

Here, as the material of the metal fibers of the metal fiber cotton-like body, in addition to stainless steel, which is the most common, stainless alloys such as chromium-nickel alloys, high nickel alloys, heat resistant alloys such as high cobalt alloys, and other heat resistant materials. A metal having corrosion resistance and corrosion resistance can be exemplified. As the dimensions of the metal fibers, those having a diameter of 20 to 150 μm and a fiber length of 20 to 250 mm can be exemplified. An example of the method for producing the metal fiber is a wire-cutting method, and in the case of this method, fibers having various fiber lengths are mixed ununiformly. Further, as the metal fiber cotton-like material, one having a bulk density of 300 to 600 kg / m ³ and a thickness of 1 to 5 mm can be exemplified. This is because when the bulk density is less than 300 kg / m ³ , the metal fibers become coarse and the glass wool scatters a lot, and when it exceeds 600 kg / m ³ , the weight of the whole metal fiber cotton material is large and the economical efficiency is poor. Further, if the thickness is less than 1 mm, the coarseness of the metal fibers becomes coarse, and the glass wool is scattered, and if it exceeds 5 mm, the needle punching process becomes difficult. The thickness is preferably 2 to 3 mm.

Next, as the diameter of the glass fiber of glass wool,
An example is 15 μm. If it is less than 5 μm, the strength per glass fiber is weak and it does not become a glass wool felt, and if it exceeds 15 μm, the strength per glass fiber is strong and it causes a feeling of touch when touching the skin, resulting in poor handling during work. Is. Preferably 7 to 13 μm
The ones are good. The fiber length of glass fiber is 50-80mm
Can be illustrated. The glass wool may have a bulk density of 100 to 200 kg / m ³ and a thickness of ³ to 15 mm. This is because if the bulk density is less than 100 kg / m ³ , the sound deadening effect becomes small, and if it exceeds 200 kg / m ³ , the flexibility is lost and a gap easily occurs between the glass wool and the outer tube. Further, if the thickness is less than 3 mm, the sound deadening effect becomes small, and if it exceeds 15 mm, it becomes difficult to wind the entire sound deadening layer around the exhaust pipe, and a gap is formed without fitting the outer circumference of the exhaust pipe. It is preferably 5 mm to 10 mm.

[Operation] According to the muffler of the internal combustion engine of claim 1, the composite mat is integrally formed by three-dimensionally intertwining the glass fibers of glass wool and the metal fibers of the cotton fiber material in the needle punched portion. Therefore, both can be wound around the outer circumference of the exhaust pipe at the same time, and the density of both fibers becomes high. Further, since the latter metal fibers are entangled three-dimensionally to prevent the metal fiber cotton-like material from bulging and maintain a high density, it is not necessary to press the metal fiber cotton-like material during winding. Further, since the sound deadening layer formed of the wound composite mat has a cotton-like outer peripheral surface and end face portions, it is in a close contact state with no gap depending on the shape of the inner peripheral surface of the outer pipe to be covered.

According to the muffler of the internal combustion engine of the second aspect, the metal fiber mat is three-dimensionally intertwined with each other in the needle punched portion of the metal fiber mat, resulting in a high fiber density.
In addition, a sound deadening layer having an arbitrary thickness can be formed by combining glass wool mat and metal fiber mat having different thicknesses.

According to the silencer of the internal combustion engine of the third aspect, in addition to the above-mentioned action, the edge portion of the metallic fiber cotton-like body of the noise reduction layer is fixed to the exhaust pipe, so that the displacement of the noise reduction layer with respect to the exhaust pipe is prevented. Further, when the fixing is performed by welding, for example, it can be fixed by a simple work called welding.

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

A large number of ventilation holes 2 are formed in a part of the exhaust pipe 1 of the internal combustion engine so as to be dispersed over the entire outer periphery of the exhaust pipe 1 at predetermined intervals.

A composite mat 5 composed of glass wool 3 and a metal fiber cotton body 4 is wound around a part of the exhaust pipe 1,
The sound deadening layer 6 is formed. This composite mat 5 is wound so that the metallic cotton-like body 4 is placed inside and covers all of the ventilation holes 2. As the glass wool 3, a glass fiber having a diameter of 9 μm, a thickness of 6 mm and a bulk density of 120 kg / m ³ was used in the examples. As the metal fiber cotton-like material 4, used was a metal fiber having a diameter of 20 to 150 μm and a fiber length of 20 to 250 mm, which was mixed ununiformly, and having a thickness of 3 mm and a bulk density of 400 kg / m ³ .

The metal fiber cotton body 4 is formed wider than the glass wool 3 so as to slightly protrude from both ends of the glass wool 3.
The glass wool 3 and the metal fiber cotton-like material 4 are superposed one by one and needle punched simultaneously from the metal fiber cotton-like material 4 side. By this needle punching process,
Since the metal fibers of the metal fiber cotton-like material 4 penetrate into the inside of the glass fibers of the glass wool 3 and are entangled three-dimensionally, the density of both fibers is increased, and the metal fibers retain the glass fibers and retain the glass fibers. Prevents scattering. Moreover, since the metal fiber cotton-like material 4 on the side of the ventilation hole 2 serves as a cushion to prevent the pulsating wave from the ventilation hole 2 from being directly transmitted to the glass fiber, the glass wool 3 is deteriorated and dispersed, and further scattered. To prevent it. The outer periphery of the sound deadening layer 6 is covered with a tubular outer pipe 7 made of a steel plate, and both ends of the outer pipe 7 are drawn into a tapered shape which becomes narrower toward the tip and welded to the exhaust pipe 1. There is. The inner peripheral surface of the outer tube 7 is in close contact with the outer peripheral surface and both end surfaces of the sound deadening layer 6 without any gap.

Next, a method for manufacturing the muffler 8 of the internal combustion engine having the above configuration will be described.

(1) The glass wool 3 is obtained by stacking the glass wool 3 and the metal fiber cotton-like material 4 and simultaneously subjecting them to needle punching.
A step of forming a composite mat 5 in which the glass fibers of 1) and the metal fibers of the metal fiber cotton-like material 4 are entangled.

The needle punching process of this example was performed by inserting the needle into the glass wool 3 from the side of the metal fiber cotton body 4. As the needles, 10 to 30 needles / cm ² of standard 25 # and 32 # were used. In addition, it is preferable that the metal fibers bite into and are entangled with 4/5 or more of the thickness of the glass wool 3 on average by this processing.

(2) A step of forming the sound deadening layer 6 by winding the composite mat 5 on the outer periphery of a part of the exhaust pipe 1 through which a large number of vent holes 2 are penetrated so as to be inside the metal fiber cotton body 4.

In this composite mat 5, the width of the metal fiber cotton-like body 4 is formed slightly larger than that of the glass wool 3 as described above, so that the edge portion of the metal fiber cotton-like body 4 protruding from the glass wool 3 is spotted at a plurality of places. Exhaust pipe 1 by welding
Fixed to.

Thus, since the composite mat 5 is integrally formed, the glass wool 3 and the metal fiber cotton-like material 4 can be wound around the outer circumference of the exhaust pipe 1 at the same time. In addition, since the metal fibers of the metal fiber cotton-like material 4 are entangled three-dimensionally to prevent the bulging and maintain a high density, the metal fiber cotton-like material 4 is pressed down or wound with a string at the time of the winding. You don't have to. Further, the entire composite mat 5 including the glass wool 3 can be easily fixed to the exhaust pipe 1 by a simple operation of welding the edge portion of the metal fiber cotton body 4 to the exhaust pipe 1. Therefore, it is extremely productive.

(3) A step of providing the outer pipe 7 that covers the outer peripheral surface and both end surfaces of the sound deadening layer 6.

First, the outer circumference of the sound deadening layer 6 is covered with a cylindrical outer tube 7. Next, both ends of the outer tube 7 are narrowed down by press working or the like to form inner peripheral surfaces of both ends so as to cover both ends of the sound deadening layer 6. Subsequently, both ends of these are welded to the exhaust pipe 1.
Since the outer peripheral surface and the end surface of the sound deadening layer 6 are cotton-like and flexible,
Depending on the shape of the inner peripheral surface of the outer tube 7, the outer tube 7 and the outer tube 7 come into close contact with each other without a gap.

According to the muffler 8 of the internal combustion engine, the pulsating waves from the ventilation holes 2 are buffered by the metal fiber cotton-like material 4 in which the metal fibers are three-dimensionally entangled and the density is increased, and the deterioration, dispersion and scattering of the glass wool 3 are carried out. As a result, the muffling effect of the muffler 8 can be prevented from being lowered. Further, since the metal fibers of the metal fiber cotton-like material 3 are three-dimensionally entangled with the glass wool 3 to prevent its vibration, the glass wool 3
Is also prevented from the viewpoint of preventing the vibration. Therefore, for example, even if the structure in which the ventilation holes 2 of the exhaust pipe 1 are enlarged or the intervals between the ventilation holes 2 are narrowed to enhance the sound absorption coefficient, the scattering of the glass wool and the like can be suppressed within the allowable range.

Further, since the outer peripheral surface and both end surfaces of the sound deadening layer 6 are in close contact with the inner peripheral surface of the outer tube 7 without a gap, no abnormal noise is generated.

[Second Embodiment] A silencer 10 for an internal combustion engine of the present embodiment shown in FIG. 5 includes a glass wool mat 11 and a metal fiber mat 12 that are needle punched separately, and the metal fiber mat 12 is inside ( Wrap around the exhaust pipe 1 so that it becomes the ventilation hole 2 side)
Is different from that of the first embodiment.

According to the muffler 10 of the internal combustion engine having the above-described configuration, the metal fiber mat 12 on the side of the vent hole 2 has three-dimensionally entangled metal fibers and is increased in density, so that the pulsating wave from the vent hole 2 is generated. Buffer well, deterioration of glass wool mat 11,
It is possible to prevent fragmentation and scattering. In the present embodiment, unlike the first embodiment, the metal fibers of the metal fiber mat 12 do not enter the glass wool of the glass wool mat 11 and suppress the latter vibration.

Further, by combining the glass wool mat 11 and the metal fiber mat 12 having different thicknesses, the sound deadening layer 13 having an arbitrary thickness can be formed.

Other functions and effects are similar to those of the first embodiment.

The present invention is not limited to the configurations of the above-described embodiments, and can be embodied by being arbitrarily modified without departing from the spirit of the invention.

The glass wool mat 11 is not limited to a needle punched product, and may be a mat-shaped product made of, for example, a binder material.

[Effects of the Invention] Since the present invention is configured as described above, it has the following excellent effects.

According to the muffler of the internal combustion engine of claim 1, the glass wool and the metal fiber cotton-like material can be wound around the outer periphery of the exhaust pipe at the same time, and the metal fiber cotton-like material can be easily attached to the outer periphery of the exhaust pipe without being pressed. Since it can be wrapped around, productivity is improved. Moreover, the pulsating wave from the ventilation holes is buffered by the metal fiber cotton-like material in which the metal fibers are three-dimensionally entangled and the density is increased, and the deterioration and scattering of the glass wool is prevented and the muffling effect of the muffler is reduced. Moreover, a structure having a high sound absorption coefficient can be provided, and no abnormal noise is generated.

According to the muffler of the internal combustion engine of claim 2, the pulsating wave from the ventilation hole is buffered by the metal fiber cotton-like material in which the metal fibers are three-dimensionally intertwined and the density is increased, and deterioration or scattering of the glass wool mat is prevented. It is also possible to prevent and easily form a sound deadening layer having an arbitrary thickness.

According to the muffler of the internal combustion engine of the third aspect, in addition to the above effects, the displacement of the muffling layer with respect to the exhaust pipe can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view of a part of a first embodiment embodying the present invention, FIG. 2 is a sectional view of the same, FIG. 3 is a sectional view showing a manufacturing process, and FIG. FIG. 5 is a sectional view of a second embodiment, and FIGS. 6 and 7 are sectional views of a conventional example. 1 ... Exhaust pipe, 2 ... Vent hole, 3 ... Glass wool, 4 ... Metal fiber cotton, 5 ... Complex mat, 6 ... Silencer layer, 7 ... Outer pipe, 8,10 ... Silencer Vessel, 11 …… Glass wool mat, 12 …… Metal fiber mat, 13 …… Silence layer.

Claims (3)

[Claims] 1. An exhaust pipe (1) having a large number of vent holes (2) partially penetrating it, a glass wool (3) and a metal fiber cotton body (4) being superposed and needle punched at the same time. The composite mat (5) in which the glass fibers of the glass wool (3) and the metal fibers of the metal fiber cotton-like body (4) are entangled with each other,
A metal fiber cotton body (4) around the outer periphery of a part of the exhaust pipe (1).
A silencer for an internal combustion engine, comprising: a sound deadening layer (6) formed by winding so as to be inside, and an outer pipe (7) covering an outer peripheral surface and both end surfaces of the sound deadening layer (6). 2. An exhaust pipe (1) having a large number of vent holes (2) formed in a part thereof, and the exhaust pipe (1) formed by needle punching a metal fiber cotton body (4). ), A sound absorbing layer (13) consisting of a metal fiber mat (12) wound around the outer circumference of the metal fiber mat and a glass wool mat (11) wound around the outer circumference of the metal fiber mat (12); A silencer for an internal combustion engine, comprising an outer pipe (7) covering the outer peripheral surface of 13) and both end surfaces. 3. A metal fiber cotton body (4) for the sound deadening layer (6).
The edge portion of the pipe is fixed to the exhaust pipe (1).
A silencer for the internal combustion engine described.