JPH0571763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust muffler for an engine, and more particularly to an exhaust muffler that reduces vibration noise caused by pressure fluctuations in exhaust gas.

[Prior Art] As is well known, as an exhaust muffler installed in a small motorcycle or the like, a pair of half cylinders are joined and fixed to each other to form an exhaust cylinder body, and the exhaust gas from the engine is passed through the exhaust cylinder body. There is something to muffle the sound.

In this type of exhaust muffler, high-frequency components in the engine exhaust sound are reduced by arranging sound-absorbing material inside the exhaust cylinder, but this method sufficiently reduces vibration noise caused by exhaust pressure fluctuations. difficult to do. Therefore, as previously disclosed in Japanese Unexamined Patent Application Publication No. 56-64114, the applicant placed a sound absorbing material on the inner circumferential surface of the exhaust cylinder to prevent the exhaust cylinder from vibrating due to pressure fluctuations in the exhaust gas. We proposed an exhaust muffler that prevents vibration noise.

[Problems to be Solved by the Invention] By the way, the vibration noise of the exhaust muffler is generated by the exhaust cylinder body vibrating due to the pressure fluctuation of the exhaust gas, and the air being vibrated thereby. Therefore, in order to effectively prevent the generation of vibration noise, it is necessary to suppress the vibration of the exhaust cylinder as much as possible and to prevent the vibration from being transmitted to the air.

This invention was made in view of the above points, and it effectively suppresses the vibrations of the exhaust cylinder body that constitutes the exhaust muffler, and also suppresses as much as possible the transmission of the vibrations of the exhaust cylinder body to the air. The purpose of the present invention is to provide an exhaust muffler that more effectively reduces noise generation.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention connects and fixes a pair of left and right outer half cylinders and an inner half cylinder to each other to form an exhaust cylinder, and the engine In the exhaust muffler, the exhaust pipe body is configured to pass through the exhaust cylinder body to muffle the sound, and an unevenness is formed on the outer surface of the outer half cylinder body of at least the side of the exhaust cylinder body located on the outside of the vehicle body. A sound-absorbing material is applied from the outside to the outer surface of the cylindrical body, and the sound-absorbing material is formed into irregularities corresponding to the irregularities formed on the outer surface of the outer half-cylindrical body, and is attached only to the outer half-cylindrical body. held in pressure contact with the outer surface of the outer semi-cylindrical body by a plate;
The sound-absorbing material and the retaining plate are formed in a shape that covers substantially the entire outer surface of the outer half-cylinder body, and furthermore, the sound-absorbing material and the retaining plate are formed in a shape that covers substantially the entire outer surface of the outer half-cylinder body, and is further formed on the retaining plate and the unevenness formed on the outer surface of the outer half-cylindrical body in the press-held state. The front retaining plate is characterized in that the front holding plate is configured to face substantially the entire outer surface of the outer semi-cylindrical body at a substantially constant interval with the sound absorbing material interposed therebetween.

[Function] In the present invention, the exhaust muffler connects and fixes a pair of left and right outer half cylinders and an inner half cylinder to each other to form an exhaust cylinder body, and at least the outer side of the exhaust cylinder body located on the outside of the vehicle body. Forming unevenness on the outer surface of the half cylinder,
A sound absorbing material is applied to the outer surface of the outer half cylinder from the outside, and this sound absorbing material is held in pressure contact with the outer surface of the outer half cylinder by a retaining plate attached to the outer half cylinder.

This outer half-cylinder body and the holding plate are formed with unevenness, so when pressure fluctuation occurs in the exhaust cylinder body due to exhaust gas, this causes the exhaust cylinder body to vibrate, but the outer half-cylinder body formed with unevenness The vibrations are suppressed by the sound absorbing material and the retaining plate formed in an uneven manner, thereby reducing the vibrations of the exhaust cylinder body.

Further, the sound absorbing material is held in pressure contact with the outer surface of the outer half cylinder by a holding plate attached to the outer half cylinder, and the sound absorbing material and the holding plate are formed in a shape that covers substantially the entire outer surface of the outer half cylinder, The entire surface of the sound-absorbing material, which has a wide area, is tightly adhered to almost the entire surface of the outer surface of the outer semi-cylindrical body, which is formed in a concave and convex manner, with a retaining plate formed in a concavo-convex manner. In addition to being able to further suppress vibration noise, most of the outer half cylinder does not vibrate directly with the air, and therefore does not vibrate the air, so the vibration noise is effectively reduced.

Furthermore, in the press-held state, the unevenness formed on the outer surface of the outer half cylinder corresponds to the unevenness formed on the holding plate, and the holding plate has a sound absorbing material over almost the entire outer surface of the outer half cylinder. Since the retaining plate is attached only to the outer semi-cylindrical body, the pressing force of the sound absorbing material is approximately uniform over the entire area, and there is no error in assembling the retaining plate. This reduces the strength of the pressure contact force of the sound absorbing material, and the vibration of the exhaust cylinder body is further effectively reduced by the sound absorbing material.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

Fig. 1 is a side view of an exhaust muffler to which the present invention is applied, Fig. 2 is a plan view, Fig. 3 is a partially omitted cross-sectional view of Fig. 1, and Fig. 4 is a side view of an exhaust muffler to which the present invention is applied. It is a sectional view of an example.

The exhaust muffler shown in the figure is installed in an internal combustion engine mounted on a small motorcycle, and is designated by the symbol 1.
1 is a connecting exhaust pipe, and the front side of this connecting exhaust pipe 1 is connected to an exhaust passage of an engine (not shown). On the other hand, an exhaust cylinder body 2 is connected to the rear side of the connecting exhaust pipe 1 .

The exhaust cylinder body 2 is formed by joining and fixing a pair of left and right outer half cylinder bodies 3 and an inner half cylinder body 4, which are formed in substantially the same shape to each other, and the outer half cylinder body 3 and the inner half cylinder body Flange portions 3a, 4 formed around the opening periphery of 4
The flange portions 3a and 4a are seam welded by strongly press-fitting the flange portions 3a and 4a while they are in contact with each other. In addition, unevenness 3b, 4b is formed on the outer half-cylinder body 3 and the inner half-cylinder body 4, reinforcing the exhaust cylinder body 2 formed in a monadic shape.

A partition wall 5 is provided inside the exhaust cylinder body 2,
The partition wall 5 defines a first expansion chamber 6 and a second expansion chamber 7, and the partition wall 5 is provided with a communication pipe 8 that communicates the first expansion chamber 6 and the second expansion chamber 7.

An exhaust conduit pipe 9 is built into the exhaust cylinder body 2 and supported by the partition wall 5 , and this exhaust conduit pipe 9 is connected to the connecting exhaust pipe 1 to guide the exhaust gas to the first expansion chamber 6 .
The exhaust from this first expansion chamber 6 is passed through a communication pipe 8 to the second expansion chamber 6.
The exhaust gas from the second expansion chamber 7 is led to the expansion chamber 7 and discharged to the atmosphere from an exhaust pipe 10 provided on the outer half cylinder 3.

A sound absorbing material 11 formed in substantially the same shape as the outer half cylinder 3 and the inner half cylinder 4 is supported on the inner peripheral surface of the outer half cylinder 3 and the inner half cylinder 4 that constitute the exhaust cylinder 2, respectively. It is supported by a plate 12. This support plate 12
A large number of holes 12a are drilled through the holes 12a, and the exhaust gas expanded in the respective expansion chambers 6 and 7 is guided to the sound absorbing material 11 through the holes 12a. The sound-absorbing material 11 used is one that can sufficiently withstand high temperatures and high-speed gas flows, and has good porous sound-absorbing performance. Although glass wool is used in this embodiment, asbestos, rock wool, etc. may also be used.

Brackets 13 and 14 are fixed to the front and rear sides of the inner half-cylinder body 4 on the installation side, which constitutes the exhaust cylinder body 2 and is attached to the vehicle body. The front bracket 13 is fixed to the engine, and the rear bracket 14 is fixed to the vehicle body. A sound absorbing material 15 is applied from the outside to the outer surface of the outer half cylinder 3 located on the non-attached side, that is, on the outside of the vehicle body.
The retaining plate 16 attached to the outer semi-cylindrical body 3
is held in pressure contact with the outer surface of the The retaining plate 16 has its mounting portion 16a applied to the nuts 17 welded to four locations on the outer surface of the outer semi-cylindrical body 3, and the washer 18
It is tightened and fixed with a tightening screw 19 screwed in through. The holding plate 16 holds the sound absorbing material 15 under pressure and protects the rider's legs from directly contacting the exhaust cylinder body 2, which is heated to a high temperature due to exhaust gas. The sound absorbing material 15 is formed slightly smaller than this retaining plate 16, and has mounting notches 15a provided at four locations on the outer periphery.
is attached so as to engage with the nut 17. The absorbent material 15 is made of the same material as the sound absorbing material 11, and in this embodiment glass wool is used.

Further, as shown in FIG. 4, the sound absorbing material 15 is held in pressure contact by fitting an elastic body 20 such as rubber into the mounting hole 16b formed in the holding plate 16, and inserting this elastic body 20 into the nut 17. It may be fixed by tightening with a tightening screw 19 via a washer 18.

In this way, the sound absorbing material 15 and the retaining plate 16 are formed in a shape that covers substantially the entire outer surface of the outer half cylinder 3, and the retainer plate 16 has the unevenness 3b formed on the outer surface of the outer half cylinder 3. Corresponding unevenness 16b is formed, and the unevenness 3b formed on the outer surface of the outer half cylinder 3 corresponds to the unevenness 16b formed on the holding plate 16 in the press-held state, and the holding plate 16 is attached to the outer half cylinder 3. They are configured to face each other at substantially constant intervals with the sound absorbing material 15 interposed therebetween over substantially the entire outer surface.

Next, the operation of this embodiment will be explained.

Exhaust pipe 1 to which the exhaust from an engine (not shown) is connected;
It is guided to the first expansion chamber 6 via the exhaust conduit 9 and is expanded. Then, it contracts through the communication pipe 8, is guided to the second expansion chamber 7, expands again, and further contracts through the discharge pipe 10 and is discharged to the atmosphere.

In this way, the exhaust gas is muffled by repeatedly expanding and contracting within the exhaust muffler, and the high frequency components of the exhaust sound are eliminated by the sound absorbing material 15 disposed on the inner peripheral surface of the exhaust cylinder body 2.

On the other hand, while the exhaust noise is being guided into the exhaust cylinder body 2, the exhaust cylinder body 2 tends to vibrate due to pressure fluctuations in the exhaust, but the vibrations are suppressed by the outer semi-cylindrical body 3 formed with convexes and convexities. The vibration of the exhaust cylinder body 2 is suppressed by the sound absorbing material 15 that is in close contact with the outer half cylinder body 3 and the holding plate 16 formed in an uneven manner.

Further, the sound absorbing material 15 is held in pressure contact with the outer surface of the outer half cylinder 3 by a retaining plate 16 attached to the outer half cylinder 3, and the sound absorbing material 15 and the retaining plate 16 are applied to substantially the entire outer surface of the outer half cylinder 3. The entire surface of the sound deadening material 15 having a wide area is tightly adhered to the entire surface of the uneven outer surface of the outer semi-cylindrical body 3 by means of a holding plate 16 formed in an uneven manner. This allows the vibration of the outer half cylinder 3 to be further suppressed, and since most of the outer half cylinder 3 does not vibrate directly with the air, the air is not vibrated, so vibration noise is effectively reduced. Reduced.

Further, in the press-held state, the unevenness 3b formed on the outer surface of the outer half-cylinder body 3 corresponds to the unevenness 16b formed on the holding plate 16, and the holding plate 16 covers approximately the entire outer surface of the outer half-cylindrical body 3. are opposed to each other at approximately constant intervals across the sound absorbing material 15, and the holding plate
6 is attached only to the outer semi-cylindrical body 3, the pressure contact force of the sound absorbing material 15 is approximately uniform over the entire area, and the pressure contact force of the sound absorbing material 15 may vary depending on the assembly error of the retaining plate 16. become less likely to become
The vibration of the exhaust cylinder body 3 is further effectively reduced by the sound absorbing material 15.

In the above embodiment, the sound absorbing material 15 was held in pressure contact only on the non-attached side of the exhaust cylinder body 2, but it goes without saying that the sound absorbing material 15 may also be provided on the attached side.

[Effects of the Invention] As described above, the present invention includes an exhaust muffler in which a pair of left and right outer half-cylinder bodies and an inner half-cylinder body are joined and fixed to each other to form an exhaust cylinder body, and at least the outside of the vehicle body of the exhaust muffler is fixed. A sound-absorbing material is applied from the outside to the outer surface of the outer half-cylinder body, and a retaining plate is attached to the outer half-cylinder body. Since it is held in pressure contact with the outer surface of the outer half-cylinder body and the outer half-cylinder body and the holding plate are formed with unevenness, when pressure fluctuation occurs in the exhaust cylinder body due to exhaust gas, the exhaust cylinder body tends to vibrate. Vibration is suppressed by the outer semi-cylindrical body formed in an uneven manner, and further suppressed by the sound absorbing material and the retaining plate formed in an uneven manner, thereby reducing vibration of the exhaust cylinder body.

In addition, the sound absorbing material is held in pressure contact with the outer surface of the outer half cylinder by a holding plate attached to the outer half cylinder, and the sound absorbing material and the holding plate are formed in a shape that covers almost the entire outer surface of the outer half cylinder. , the entire surface of the sound-absorbing material having a wide area is in close contact with the retaining plate formed in the concavo-convex shape on the outer surface of the outer semi-cylindrical body, which prevents vibrations of the outer half-cylindrical body In addition, most of the outer semi-cylindrical body does not vibrate directly with the air, and therefore does not cause the air to vibrate, thereby effectively reducing vibration noise.

Furthermore, in the press-held state, the unevenness formed on the outer surface of the outer half cylinder corresponds to the unevenness formed on the holding plate, and the holding plate has a sound absorbing material over almost the entire outer surface of the outer half cylinder. Since the retaining plates were attached only to the outer semi-cylindrical body, the pressing force of the sound absorbing material was approximately uniform over the entire area, and due to assembly errors of the retaining plates, The pressure contact force of the sound absorbing material is reduced, and the vibration of the exhaust cylinder body can be further effectively reduced by the sound absorbing material.

[Brief explanation of drawings]

Fig. 1 is a side view of an exhaust muffler to which the present invention is applied, Fig. 2 is a plan view, Fig. 3 is a partially omitted cross-sectional view of Fig. 1, and Fig. 4 is a side view of an exhaust muffler to which the present invention is applied. It is a sectional view of an example. DESCRIPTION OF SYMBOLS 1... Connection exhaust pipe, 2... Exhaust tube body, 3... Outer half cylinder body, 4... Inner half cylinder body, 9... Exhaust conduit pipe, 10... Exhaust pipe, 11, 15... Sound absorbing material ,1
6...Retaining plate, 19...Tightening screw.

Claims (1)

[Claims] 1. An exhaust muffler in which a pair of left and right outer half-cylinder bodies and an inner half-cylinder body are joined and fixed to each other to form an exhaust cylinder body, and the exhaust gas of the engine is passed through the exhaust cylinder body to muffle noise. An unevenness is formed on the outer surface of the outer half-cylinder body located at least on the outside of the vehicle body of the exhaust cylinder body, and a sound-absorbing material is applied from the outside to the outer surface of the outer half-cylinder body, and the sound-absorbing material is applied to the outer half-cylinder body. The sound absorbing material and the retaining plate are held in pressure contact with the outer surface of the outer half cylinder body by a holding plate formed with unevenness corresponding to the unevenness formed on the outer surface of the body and attached only to the outer half cylinder body, and the sound absorbing material and the holding plate are The outer semi-cylindrical body is formed in a shape that covers substantially the entire outer surface of the outer semi-cylindrical body, and furthermore, the unevenness formed on the outer surface of the outer half-cylindrical body corresponds to the unevenness formed on the retaining plate in the press-held state, and the above-mentioned An exhaust muffler characterized in that the holding plates are configured to face each other at substantially constant intervals across substantially the entire outer surface of the outer semi-cylindrical body with the sound absorbing material interposed therebetween.