JPS58202322A - Discharge silencer of internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce a discharge noise and discharge pulsation and to decrease the output loss of an engine by providing a noise absorbing material layer filled between a casing and a cylinrical structure and vibrating noise insulation plates provided as capable of vibrating freely. CONSTITUTION:Exhaust gas discharged from an internal-combustion engine, etc. passes through a discharge pipe 4 and is introduced into a casing 1 through an exhaust gas guide port 2. The introduced exhaust gas hits the mass bodies 13 of vibrating noise insulation plates 11 and is guided to a cylindrical structure side 6 outward in the radial direction, passes through air holes 12a of thin plates 12, flows in succession downstream through a discharge passage 7, and is exhausted from an exhaust port 5 through an exhaust gas discharge port 3 into the atmosphere. The cylindrical structure 6 is provided with many air holes 6a and its cross section is formed into V-shaped ruggedness, and sound waves are repeatedly reflected by means of the cylindrical structure 6, casing 1, and vibrating noise insulation plates 11, thereby the same effect is available as that a noise absorbing material layer 8 is expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust silencing device for an internal combustion engine, and more particularly to an exhaust silencing device for an internal combustion engine that can significantly reduce exhaust noise and exhaust pulsation, and further reduces engine output loss.

The following methods are available for conventional exhaust silencing.

Expansion method (a) expands the waves into the cavity and muffles the acoustic energy density by thinning the fabric and constricting it at the edge of the cavity.

(b) A resonance method in which a resonance cavity is provided in parallel with the exhaust pipe line and connected through a communication hole or the like, and the sound energy is consumed by resonance.

(e) A sound absorption method that absorbs sound by converting acoustic energy into thermal energy using sound absorbing materials.

(d) An interference method in which the acoustic tube is branched to provide a path difference, and the sound waves are split and then merged again to completely attenuate the sound waves due to sound interference.

Conventionally, these methods have been appropriately combined to completely muffle the exhaust gas. However, none of the conventional exhaust mufflers have a sufficient muffling effect, and they do have a certain muffling effect. In some cases, the exhaust flow is diverted, branched, or excessively throttled, which obstructs the exhaust flow and results in loss of output from the internal combustion engine.

The present invention has been devised to effectively solve all of the above-mentioned conventional problems, and an object of the present invention is to provide an internal combustion engine that can significantly reduce exhaust noise and exhaust pulsation, and also reduce output loss due to gradual opening. is to provide engine exhaust china equipment.

Preferred embodiments of the present invention are attached below.
C (r>- and -) will be explained in detail.

In Fig. 1, 1 is a spindle-shaped casing whose middle part is expanded and formed, and an exhaust inlet 2 is provided at one end of the casing.
However, an exhaust outlet 3 is formed at the other end, an exhaust pipe 4 is inserted and connected to the exhaust inlet 2, and a discharge pipe 5 is connected to the exhaust outlet 3.

Inside the casing 1, there is a spindle cylinder shape along the inner wall of the casing 1.
A bellows-shaped cylindrical structure 6 with uneven waves and a V-shaped cross section
is provided. A straight exhaust flow path 7 is formed in the casing 1 by this cylindrical structure 6, in which enlarged diameter portions 7a and reduced diameter portions 7b are alternately repeated from the exhaust inlet 2 toward the exhaust outlet 3. be done.

Further, a sound absorbing material layer 8 filled with a sound absorbing material is formed between the cylindrical structure 6 and the casing 1.

The sound-absorbing material layer 8 includes a heat-insulating sound-absorbing material 9 such as glass wool or asbestos disposed on the inner wall surface of the casing 1;
It is made up of two types of sound absorbing materials: a sound absorbing material 10 such as lathe scraps, which has a larger gap than glass wool, which is filled on the side of the cylindrical structure 6 of the 1+. Further, the cylindrical structure 6 is provided with a large number of ventilation holes 6a, and these ventilation holes 6a allow sound waves to freely pass between the sound absorbing material layer 8 and the exhaust flow path 7. There is.

Further, in the enlarged diameter portion 7a of the exhaust flow path 7, vibration sound insulating plates 11 are provided at every other place along the exhaust flow path 7v. The vibration sound insulating plate 11 is provided perpendicularly to the exhaust flow path 7 so as to block it. As shown in FIGS. 1 to 3, the vibration shielding plate 11 includes a thin plate 12, which has a large number of ventilation holes 12ae in its distal portion and whose peripheral edge is fixedly supported by the cylindrical structure 6 by welding or the like. It is composed of a disk-shaped relatively thick mass body 13 that is integrally attached to the center of a thin plate 12. The thin plate 12 is provided with a large number of ventilation holes 12°, and since the thin plate 12 is made of a highly elastic metal, the thin plate 12 functions as a spring that vibrates the mass body 13 in the uniaxial direction of the casing. It is supposed to be done.

Next, the operation of this embodiment will be described.

Exhaust gas discharged from an internal combustion engine or the like passes through the exhaust pipe 4 and enters the casing 1 from the exhaust gas introduction port 2. The introduced exhaust gas roars into the mass body 13 of the vibration sound insulating plate 11, is guided to the radially outward side of the cylindrical structure 6, passes through the ventilation hole 12ak of the thin plate 12, and sequentially flows downstream through the exhaust flow path 1. flowing to the side,
Then, it is discharged into the atmosphere from the discharge pipe 5 via the exhaust m outlet 3. In the muffler of the present invention, the exhaust flow path 7 is formed straight from the exhaust pipe 4 toward the discharge pipe 5, and the vibration sound insulating plate 11 that blocks the exhaust flow path 7 is provided in the enlarged diameter portion 7m. I! 7 Sound insulation board 11 has many ventilation holes 1
2a, the exhaust gas flows smoothly through the exhaust flow path 7 without being obstructed by the vibration sound insulating plate 11 or the like.

Therefore, the output loss of the internal combustion engine caused by this muffler is extremely small.

On the other hand, the sound waves (
Exhaust noise) is silenced as follows.

The thin plate 12 of the vibration sound insulation board 11 acts as a spring to support the mass body 13, so when the sound waves (and pulsations associated with exhaust air) hit the vibration sound insulation board 11, the mass (413 is a vibration in the 1-axis direction of the casing). ia, the sound # (and exhaust pulsation) energy is absorbed as vibration energy of the vibration sound insulating plate 11.

In addition, the cylindrical structure 6 has a large number of ventilation holes 6 &' and is formed in a V-shaped uneven wave shape in cross section, so that the sound waves are
The cylindrical structure 6, the casing 1, and the vibration a[will be reflected repeatedly by the tone plate 11, producing the same effect as when the sound absorbing material layer 8 is expanded, and the energy of the sound wave is converted into thermal energy by the sound absorbing material 9, 10 is effectively absorbed.

Furthermore, while the sound waves propagate through the exhaust flow path 1, they are narrowed down by the ventilation holes 12& of the sound insulating plate 11, and are emitted from the ventilation holes 12a.
The expanded W is given back to the exhaust flow path 7 between the J sound insulating plates 11, thereby suppressing the pressure vibration of the sound wave. In particular, the middle part 7 of the exhaust flow path 1'
Since c is formed by expansion, the acoustic energy density is greatly diluted due to the expansion of the sound wave (+'i sound effect is large.

Furthermore, the air hole 6a of the cylindrical structure 6 acts as a mass fSi, and the sound absorbing material layer 8 acts as a resonant cavity (spring), and the energy of the sound wave is consumed by resonance. The exhaust noise is significantly reduced by the above-mentioned silencing effect.

In addition, in the above embodiment, the vibration sound damping plate 11 is the thin plate 1.
2 and a mass body 13, but instead of the thin plate 12, an elastic rod-shaped body, a wire member, or a leaf spring is used to vibrate the mass bodies 1 and 3 to the planar structure 6. It may be supported freely. Of course, the vibration and sound insulating plate may be of an integral structure, and in the middle part 7c of the expanded exhaust flow path 7, it is possible to provide the vibration and sound insulating plate 11t at the reduced diameter part 7b of the cylindrical structure 6. You can also do this.

As is clear from the above explanation, according to the present invention, exhaust noise and exhaust pulsation of an internal combustion engine can be significantly reduced.
In addition, since the exhaust flow is not obstructed, the loss of output of the internal combustion engine is small, and the structure is simple, and it can be easily manufactured and has excellent effects, such as being highly useful.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the device according to the present invention;
FIG. 2 is an enlarged sectional view of the same portion, and FIG. 3 is a front view of the vibration and sound insulating plate shown in FIG. 1. In the figure, 1 is a casing, 2 is an exhaust inlet, 3 is an exhaust outlet, 6 is a cylindrical structure, 6a is a ventilation hole, 1 is an exhaust flow path, 7
7b is a reduced diameter portion, 8 is a sound absorbing material layer, and 11 is a vibration sound insulating plate. Patent applicant: Makoto Minamidate (2 others) Agent: Nobuo Kinuya, patent attorney

Claims (1)

[Claims] A cylindrical casing which has a combined air intake at one end and an exhaust outlet at the other end to form an exhaust flow path, and whose middle part is expanded and formed along the inner surface of the casing. , a bellows-like hook-shaped structure provided to alternately form diameter-expanding portions and concave portions, and a large number of vents provided in the cylindrical structure.
rL, a sound absorbing material layer filled and formed between the casing and the cylindrical structure, and a vibrating sound plate provided so as to be able to freely vibrate across the exhaust flow path. Exhaust silencer for internal combustion engines.