JPS593132Y2 - Exhaust silencer for internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust muffler for an internal combustion engine suitable for vehicles, particularly motorcycles.

In the exhaust muffler, for example,
As shown in Publication No. 709, a sound absorbing material is annularly welded to the inner surface of an outer cylinder, a partition plate that partitions a part of the exhaust passage formed there is fixed to the inside of the outer cylinder, and a It is known that the inner cylinder, through which the exhaust gas flows collectively, is fixed.

In this case, if a sound-absorbing material is welded to the inner surface of the inner cylinder in the same way as the inner surface of the outer cylinder, the sound-absorbing material of the inner cylinder absorbs the exhaust gas passing through it, and the sound-damping effect as a whole can be enhanced, but on the other hand, , separate sound-absorbing materials must be provided on the inner surfaces of the inner and outer cylinders, which increases the amount of sound-absorbing materials used, complicates the structure, and increases costs. There are problems such as a decrease in effective volume.

In addition, in the above-mentioned publication, the inner surface of the sound absorbing material of the outer cylinder is directly exposed to the expansion chamber inside the outer cylinder, so when it receives the fluid pressure of the exhaust, it tends to scatter and peel off from the inner surface of the outer cylinder. be.

The present invention has been proposed in view of the above, and it is an object of the present invention to provide an exhaust muffler for an internal combustion engine, which has a simple structure and can eliminate all of the above-mentioned problems of conventional ones.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Glass wool 2 as a sound absorbing material is welded to the inner surface of the outer cylinder 1 of the silencer in a ring shape with a predetermined thickness. A pair of punching plates 3 each having a semicircular cross section and having a small ventilation hole 4 formed therein are facing each other and covered with a polymer, and the edges of these punching plates 3 are fixed to the inner surface of the outer cylinder 1.

A notched circular partition plate 5 is fixed to the middle part of the inner surface of the outer cylinder 1 in a direction substantially perpendicular to the longitudinal direction thereof, and a concave edge of the partition plate 5 extends in the longitudinal direction inside the outer cylinder 1. The middle part of the guide plate 6 having a concave cross section is fixed.

Both side edges of the guide plate 6 are fixed to the inner surface of the punching plate 3, and a sound absorption passage 7 is formed by the guide plate 6 and a part of the punching plate 3. Exhaust gas is collected and circulated through this sound absorption passage 7. A part of the exhaust noise flowing through the exhaust gas is absorbed by the glass wool 2 on the inner surface of the outer cylinder 1.

An exhaust introduction pipe 8 connected to an exhaust port of an internal combustion engine is fitted into one end of the outer cylinder 1, and a muffler cylinder 9 opened to the atmosphere is fitted into the other end.

Next, the operation of one embodiment of the present invention will be described. Exhaust gas generated by the operation of an internal combustion engine (not shown) flows from the exhaust port through the exhaust introduction pipe 8 into the expansion chamber in the outer cylinder 1. While being expanded, the exhaust gas is primarily sound-absorbed by the glass wool 2 on the inner surface of the outer cylinder 1.

The exhaust gas whose sound has been primarily absorbed as described above is guided to the sound absorption passage 7 defined by the guide plate 6 and a part of the punching plate 3 and which corresponds to the inner cylinder of a conventional muffler. 7, the exhaust sound is secondarily absorbed by the glass wool 2 facing the sound absorption passage 7.

At that time, a part of the exhaust gas can move inside the glass wool 2 in the circumferential direction of the outer cylinder, that is, in the circumferential direction of the sound-absorbing passage 7, and flow out of the sound-absorbing passage 7. Therefore, if only the glass wool 2 facing the sound-absorbing passage 7 First, the surrounding glass wool 2 also provides a sufficient sound absorption effect for the exhaust flow.

The exhaust gas that has passed through the sound absorbing passage 7 flows into the muffling tube 9, where it is expanded and bypassed the passage, and finally the sound waves are made to interfere with each other to be muffled and discharged from the exhaust port.

As described above, according to the present invention, a sound absorbing material such as glass wool 2 is welded to the inner surface of the outer cylinder 1 in a ring shape with a predetermined thickness,
Furthermore, in the exhaust muffler for an internal combustion engine, a partition plate 5 is fixed to the outer cylinder 1 to partition a part of the exhaust passage formed therein, and a large number of ventilation holes 4 are bored in the inner surface of the sound absorbing material. A guide plate 6 extending in the longitudinal direction of the outer cylinder 1 is fixed to the punching plate 3 and the partition plate 5, and the guide plate 6 and the punching plate 3 are covered with a polymer. Inside the outer cylinder 1 by a part of
Since the sound absorbing passage 7 through which the exhaust gas collectively flows is defined, the outer cylinder 1
A sound-absorbing material such as glass wool 2, which is welded to the inner surface of the outer cylinder to prevent noise, is used as a sound-absorbing material for the sound-absorbing passage 7, which corresponds to the inner cylinder of the conventional muffler, that is, to absorb sound from the exhaust flow flowing through the inner cylinder. Therefore, the structure is simplified by reducing the absolute amount of sound-absorbing material compared to the conventional sound-absorbing material welded to each inner surface of the outer cylinder and inner cylinder. Of course, the cost can be reduced, and the outer cylinder 1
It is possible to secure a wide effective volume of the expansion chamber for noise reduction.

In particular, since the punching plate 3 is polymerized and coated on the inner surface of the sound-absorbing material, even if the large flow pressure of the exhaust gas flowing through the sound-absorbing passage 7 acts on the sound-absorbing material, the punching plate 3 prevents the sound-absorbing material from scattering. In addition, the guide plate 6 can be fixed not only to the partition plate 5 but also to the punching plate 3, so that the plate 6 can be stably supported.

Moreover, a part of the exhaust gas flowing through the sound absorbing passage 7 enters the sound absorbing material having a predetermined thickness through the small hole 4 of the punching plate 3, and passes there in the circumferential direction of the outer cylinder 1, that is, around the circumference of the sound absorbing passage 7. Since it can flow along the direction and flow out of the sound absorption passage 7, not only the sound absorption material facing the sound absorption passage 7 but also the surrounding sound absorption material absorb the sound from the exhaust flow flowing through the sound absorption passage 7. Therefore, a sufficient sound absorbing effect on the exhaust flow can be obtained without special welding of a sound absorbing material to the inner surface of the guide plate 6.

[Brief explanation of the drawing]

Figure 1 is a partially cutaway plan view of the silencer of the present invention, and Figure 2 is the
It is a sectional view taken along the line II-II. 1...Outer tube, 2...Glass wool as a sound absorbing material, 3...Punching plate, 4...
...Small hole, 5...Partition plate, 6...
・Guidance board, 7...Sound absorption passage.

Claims (1)

[Scope of utility model registration request] A sound absorbing material such as glass wool 2 is annularly welded to the inner surface of the outer cylinder 1 to a predetermined thickness, and a partition plate 5 is fixed inside the outer cylinder 1 to partition a part of the exhaust passage formed therein. In an engine exhaust silencer, a punching plate 3 having a large number of small ventilation holes 4 is polymerized and coated on the inner surface of the sound absorbing material, and the punching plate 3 and the partition plate 5 have a structure in which the inside of the outer cylinder 1 is covered. A guide plate 6 extending in the longitudinal direction is fixedly attached to the punching plate 3.
An exhaust muffler for an internal combustion engine, which defines a sound absorption passage 7 in an outer cylinder 1 through which exhaust gas collectively flows.