JPH079172B2 - Silencer for internal combustion engine - Google Patents

Description

The present invention relates to a silencer for an internal combustion engine mounted on a motorcycle or the like.

[Conventional technology]

Generally, a muffler 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 it to resonate in a resonance chamber. That is, the glass wool is filled in the outside of the punch plate forming the exhaust passage and absorbs the exhaust sound passing through the holes of 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 the exhaust sound.

[Problems to be Solved by the Invention]

However, in the conventional silencer for an internal combustion engine of this kind, a defined filling chamber for filling glass wool and a resonance chamber for resonating exhaust noise must be individually formed, so that the structure is There was a problem that it became complicated.

[Means for Solving the Problems]

The present invention has been made in view of such circumstances, and provides a silencer for an internal combustion engine capable of reducing exhaust noise with a simple structure. A muffler for an internal combustion engine according to the present invention comprises a muffler connected to an extension side end of an exhaust pipe extending from the engine, and a Helmholtz resonator connected to the exhaust pipe is arranged in the muffler. Helmholtz resonator,
A porous material connected to the exhaust pipe and forming a part of the exhaust passage as a peripheral wall, and a porous material disposed outside the porous material to seal the periphery of the porous material and to form an annular space around the porous material. And a cylindrical member that forms an air chamber composed of a chamber.

[Action]

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

〔Example〕

An embodiment of the present invention will be described in detail below 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 an enlarged main part of the same. The reference numeral 1 in these drawings is for a motorcycle. A muffler is shown, and this muffler 1 is composed of an exhaust pipe 2 having one end 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 on the front side of the engine, extend in the horizontal direction toward the rear of the vehicle, and then extend upward. The silencer 3 has a megaphone shape whose diameter gradually increases toward the rear part, and is connected so as to slightly extend upward.
A part of the muffler 3 that extends upward of the exhaust pipe 2 is inserted in the front part. The Helmholtz resonator according to the present invention is connected to a portion of the exhaust pipe 2 that extends rearward in the silencer 3. Further, although not shown, inside the muffler 3, an expansion chamber for reducing exhaust noise is formed by a partition member.

Reference numeral 5 denotes a porous material that forms a part of the peripheral wall of the exhaust passage, and the porous material 5 is connected to the rear end portion of the exhaust pipe 2 that extends rearward in the silencer 3. The porous material 5 has a cylindrical shape and is supported by the exhaust pipe 2 by inserting the rear end of the exhaust pipe 2 into the front end opening portion thereof, and the rear end portion is connected to the exhaust pipe 2 via a tubular member described later. Supported.

Here, as the porous material 5, a porous aluminum sintered material obtained by sintering aluminum powder, a metal fiber felt in which metal fibers are solidified with a binder such as a solder into a void state, or a spongy metal is used. be able to.

Reference numeral 7 denotes an outer cylinder that covers the porous material 5 and forms an annular air chamber 8 on the outer side. Reference numeral 15 denotes a holding portion that holds the rear end portion of the porous material 5. The outer cylinder 7 and the holding portion 15 And constitute a tubular member according to the present invention. The outer cylinder 7 is formed to be longer than the porous material 5, a front end portion thereof is provided with a small-diameter mounting portion 19 into which the exhaust pipe 2 is fitted, and a rear end portion thereof is provided with the holding portion 15. There is. 16 is a welded portion for welding the rear end portion of the porous material 5 to the holding portion 15, 17 is a welded portion for welding the front end portion of the porous material 5 to the outer cylinder 7, and 18 is a front end portion of the outer cylinder 7. Exhaust pipe 2 with mounting part 19 provided
It is a welded part that is welded to. The tubular member including the outer cylinder 7 and the holding portion 15 is held coaxially with the exhaust pipe 2 and the porous material 5.

The welding of the welded portions 16 to 18 is continuously performed over the entire circumference so that the air chamber 8 is an airtight space opened only by the voids of the porous material 5. That is, the tubular member closes the periphery of the porous material 5 and forms the air chamber 8 formed of an annular empty chamber around the porous material 5.

In the silencer of the internal combustion engine configured as above,
Since the peripheral wall of the exhaust passage through which the exhaust gas passes is formed of the porous material 5, the sound wave energy, that is, the exhaust sound can be absorbed by the large number of voids in the porous material 5. Also,
The annular air chamber 8 on the outer side of the porous material 5 is formed as an airtight cavity,
Since the void of the porous material 5 can be a small opening of this cavity, the Helmholtz resonator can be formed by the porous material 5 and the air chamber 8.

Therefore, the air chamber 8 can function as a resonance chamber, so that the exhaust sound propagated in the exhaust passage can be resonantly damped. That is, the void of the porous material 5 is used as an opening of the resonator, and the other portion is used as a partition member that defines the air chamber 8 that is a cavity.

Moreover, since the outer cylinder 7 is housed inside the silencer 3 and is not exposed to the outside, the appearance is not spoiled.

In the above embodiment, the example in which the peripheral wall of the exhaust pipe 2 is formed of the porous material 5 has been described, but the present invention is not limited to this, and a part of the peripheral wall of the exhaust passage in the silencer 3 may be formed. The porous material 5 may be used, and the same effect can be obtained.

〔The invention's effect〕

As described above, in the silencer for an internal combustion engine according to the present invention, a silencer is connected to an extension side end of an exhaust pipe extending from the engine, and a Helmholtz resonator connected to the exhaust pipe is arranged in the silencer. The Helmholtz resonator is made of a porous material that is connected to the exhaust pipe and serves as a peripheral wall of a part of the exhaust passage, and is disposed outside the porous material to seal the periphery of the porous material. In addition, because it is composed of a cylindrical member that forms an air chamber consisting of an annular void around the porous material, the exhaust sound is absorbed by the porous material and the air chamber functions as a resonance chamber to resonate the exhaust sound. Can be attenuated.

Therefore, since the resonance chamber can be formed by using the porous material that absorbs the exhaust sound, the exhaust sound can be formed with a simple structure as compared with the conventional one in which the filling chamber of the sound absorbing material and the resonance chamber are individually formed. Can be reduced.

Further, since the Helmholtz resonator is covered by the peripheral wall portion of the silencer, the exhaust sound transmitted from the silencer to the outside can be further reduced. Furthermore, since the hollow portion in the silencer can be used as the installation space for the Helmholtz resonator, it is not necessary to separately secure the installation space. Therefore, the silencer does not become large in size.

Furthermore, since the Helmholtz resonator is separated from the engine by the extension dimension of the exhaust pipe, it does not interfere with the engine. Moreover, the Helmholtz resonator having a shape in which a part of the exhaust passage is thickened is hidden by the muffler, and the appearance is not deteriorated.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a muffler for an internal combustion engine according to the present invention, and FIG. 2 is a cross-sectional view showing an enlarged main part of the same. 2 ... Exhaust pipe, 3 ... Silencer, 5 ... Porous material, 7 ...
Outer cylinder, 8 ... Air chamber, 15 ... Holding part.

Claims (1)

[Claims] 1. A silencer is connected to an extension side end of an exhaust pipe extending from an engine, and a Helmholtz resonator connected to the exhaust pipe is arranged in the silencer. The Helmholtz resonator is A porous material which is connected to the exhaust pipe and serves as a peripheral wall of a part of the exhaust passage, and a porous material which is arranged outside the porous material to seal the periphery of the porous material and to form an annular space around the porous material. A silencer for an internal combustion engine, comprising: a cylindrical member that forms an air chamber including a chamber.