JPS6238815A - Silencer device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce exhaust noise with simple structure, by forming a part of the circumferential wall of an exhaust passage with a porous member and forming an annular air chamber outside the porous member so as to absorb the exhaust noise by the porous member and make the air chamber work as a resonant chamber. CONSTITUTION:A silencer device comprises an exhaust pipe 2, a silencer connected to one end of the exhaust pipe 2 and others. In the above device a porous member 5, for example, such as porous alminium sintered material or the like which defines a part of the circumferential wall of the exhaust pipe 2, is welded 6 to a portion which is the middle portion of the exhaust pipe 2 and extends in horizontal direction. Then, an outer cylinder 7 covering the porous member 5 is provided, and an annular air chamber 8 is defined therebetween. At that time, both ends of the outer cylinder 7 are closed by partition walls 9, 9, the exhaust pipe 2 and the outer cylinder 7 are welded together via welds 10, 11 so that the air chamber 8 becomes an air-tight space. Thereby, a Helmholtz resonator can be defined by the porous member 5 and the air chamber 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a muffling device for an internal combustion engine installed in a motorcycle or the like.

[Conventional technology]

Generally, a silencer for an internal combustion engine for a motorcycle is configured to reduce exhaust noise by absorbing sound with a sound absorbing material such as glass wool or by causing resonance in a resonance chamber. That is, the glass wool is filled on the outside of the punch plate that forms the exhaust passage, and absorbs the exhaust sound passing through the holes in the punch plate. Further, the resonance chamber is formed in a portion of the intake passage that is not filled with glass wool, and resonates and attenuates exhaust noise.

[Problem that the invention seeks to solve]

However, in the conventional silencer for this type of internal combustion engine, a defined filling chamber for filling glass wool and a resonance chamber for resonating the exhaust sound must be formed separately, so the structure is complicated. The problem was that it became complicated.

Means for Solving Problem c] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a muffling device for an internal combustion engine that can reduce exhaust noise with a simple structure. A muffler for an internal combustion engine according to the present invention includes a peripheral wall of a part of an exhaust passage made of a porous material, and an annular air chamber formed outside the peripheral wall.

[Effect]

In the present invention, exhaust sound is absorbed by the porous material, and the air chamber functions as a resonance chamber to resonancely attenuate the exhaust sound.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a partial cross-sectional view showing a silencer for an internal combustion engine according to the present invention, and Fig. 2 is a cross-sectional view showing the same enlarged main part. This silencer 1 is comprised of an exhaust pipe 2 whose one end is connected to an exhaust port of an engine (not shown), a muffler 3 connected to the other end of the exhaust pipe 2, and the like. The exhaust pipe 2 is formed so as to descend from the front side of the engine, extend horizontally toward the rear of the vehicle body, and then move upward. The muffler 3 has a megaphone shape whose diameter gradually increases toward the rear, and is connected slightly upward.

An upwardly directed portion of the exhaust pipe 2 is inserted into the front part of the muffler 3.

Further, although not shown, an expansion chamber and the like for reducing exhaust noise are formed inside the muffler 3 by a partition member.

Reference numeral 5 denotes a porous material forming a peripheral wall of a part of the exhaust passage, and in the embodiment, it is provided at the middle part of the exhaust pipe 2, which extends in the horizontal direction. This porous material 5 has a cylindrical shape, and is held in the middle of the exhaust pipe 2 by welding both end faces to the exhaust pipe 2 at welded portions 6, 6. Here, as the porous material 5, a porous aluminum sintered material made by sintering aluminum powder, metal fiber felt made by solidifying metal fibers with voids with a binder such as solder, or a spongy metal is used. be able to.

Reference numeral 7 designates an outer cylinder that covers the porous material 5 and forms an annular air chamber 8 on the outside, and 9.9 represents a partition member having an annular U-shaped cross section that closes both ends of the outer cylinder 7.

That is, the outer cylinder 7 is formed longer than the porous material 5, and is held coaxially with the exhaust pipe 2 by partition members 9, 9 interposed between both ends of the outer cylinder 7 and the exhaust pipe 2. has been done. 10 is a welding part for welding the exhaust pipe 2 and the partition member 9.9, and 11 is a welding part for welding the partition member 9.9 and the outer cylinder 7. Welding of these welded portions 10, 11 is performed continuously over the entire circumference so that the air chamber 8 is an airtight space opened only by the voids of the porous material 5.

In the internal combustion engine silencer configured in this way,
Since the peripheral wall of the exhaust passage through which the exhaust gas passes is formed of the porous material 5, the numerous voids in the porous material 5 can absorb the energy of the sound waves, that is, the exhaust sound. Also,
An annular air chamber 8 outside the porous material 5 is an airtight cavity,
Since the void in the porous material 5 can be a small opening of this cavity, the porous material 5 and the air chamber 8 can form a Helmholtz type resonator.

Therefore, since the air chamber 8 can function as a resonance chamber, the exhaust sound propagated into the exhaust passage can be attenuated by resonance. That is, the voids in the porous material 5 are used as openings of the resonator, and the other parts are used as partition members that define the air chambers 8 that are cavities.

FIG. 3 is a partial cross-sectional view showing another embodiment, and FIG. 4 is a cross-sectional view showing an enlarged main part.
Components that are the same as or equivalent to those shown in the figures and FIG. In this embodiment, a porous material 5 is provided at the rear end of the portion of the exhaust pipe 2 that is inserted into the muffler 3. Therefore, the outer cylinder 7
A holding portion 15 for holding the rear end portion of the porous material 5 is provided. Reference numeral 16 holds the rear end of the porous material 5 to the holding portion 15.
17 is a welding part where the front end of the porous material 5 is welded to the outer cylinder 7; 18 is a welding part where the mounting part 19 provided at the front end of the outer cylinder 7 is welded to the exhaust pipe 2. It is.

Therefore, in this embodiment, the outer cylinder 7 is not exposed to the outside, so that the appearance is not impaired.

Although the above embodiment describes an example in which the peripheral wall of the exhaust pipe 2 is formed of the porous material 5, the present invention is not limited to this. It may be formed of porous material 5, and similar effects can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, a part of the circumferential wall of the exhaust passage is formed of a porous material, and an annular air chamber is formed on the outside of the peripheral wall of the exhaust passage.

In addition to absorbing exhaust noise, the air chamber functions as a resonant chamber to attenuate the exhaust sound resonantly.

Therefore, since the resonance chamber can be formed using a porous material that absorbs exhaust noise, the structure is simpler than the conventional structure in which a chamber filled with sound-absorbing material and a resonance chamber are formed separately. can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing a silencer for an internal combustion engine according to the present invention, FIG. 2 is a cross-sectional view showing an enlarged main part of the same, and FIG. 3 is a partial cross-sectional view showing another embodiment. , FIG. 4 is an enlarged cross-sectional view of the main part. 2... Exhaust pipe, 3... Silencer, 5... Porous material, 7... Outer cylinder, 8... Air chamber.

Claims (1)

[Claims] A silencer for an internal combustion engine, in which a peripheral wall of a portion of an exhaust passage is formed of a porous material, and an annular air chamber is formed outside the porous material.