JP2509686Y2 - Silencer for internal combustion engine - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for an internal combustion engine having a function of purifying exhaust gas discharged from the internal combustion engine.

[0002]

2. Description of the Related Art In many conventional internal combustion engines, a monolith type exhaust gas purifying device is provided upstream of the exhaust gas passage and a silencer is provided downstream thereof. As described above, in the case where the monolith type exhaust gas purifying device and the silencer are arranged in series in the exhaust passage of the internal combustion engine, the exhaust inertia effect cannot be obtained, and the flow resistance of the exhaust gas purifying device causes exhaust port back Since the pressure tends to be high and the cost is high, in a small internal combustion engine or the like mounted on a motorcycle, as described in JP-A-2-221623, an exhaust gas that connects an exhaust port and a silencer is used. The catalyst was stretched over the inner surface of the tube. In the case where the catalyst is stretched on the inner peripheral surface of the exhaust pipe, although the exhaust gas inertial effect can be extracted to improve the output and efficiency, the structure is also complicated and the cost cannot be avoided.

[0003]

SUMMARY OF THE INVENTION The present invention relates to an improvement of an exhaust system of an internal combustion engine which overcomes the above problems, and a silencer main body has a substantially cylindrical shape, and an axial direction is provided in a central portion thereof. A central tubular portion directed toward the center and an intermediate tubular portion arranged substantially concentrically around the central tubular portion, and the central tubular portion and the intermediate tubular portion sandwich a porous catalyst between thin inner and outer tubular tubes having a large number of small holes. Respectively, one end of the central tubular portion is connected to an exhaust port of an internal combustion engine, a communication opening is formed at the other end of the central tubular portion, and a communication opening is formed at one end of the intermediate tubular portion, An exhaust opening is formed at the other end of the silencer body.

Since the present invention is constructed as described above, the exhaust gas discharged from the exhaust port of the internal combustion engine and flowing into the central tubular portion from the one end side of the central tubular portion flows in the central tubular portion. It flows toward the other end side, flows into the annular space between the intermediate tubular portion and the central tubular portion through the communication opening of the central tubular portion, and flows in the annular space in the direction of the exhaust gas in the central tubular portion. The air flows in the opposite direction toward the one end side, flows into the space between the silencer body and the intermediate cylinder part from the communication opening of the intermediate cylinder part, flows in the space toward the other end side, and flows to the outside air from the exhaust opening. Is discharged to.

As described above, in the present invention, the exhaust gas extends in a meandering flow path from the central portion to the outer peripheral portion, the throttling effect of the communication opening, and the small inner and outer cylinders of the central cylinder portion and the intermediate cylinder portion. The effect of absorbing pressure fluctuations from the holes to the catalyst significantly reduces the exhaust noise level.

Further, in the present invention, since the catalyst sandwiched between the central tubular portion and the intermediate tubular portion is in wide contact with exhaust gas through a large number of small holes on both sides of the tubular portion, purification is performed. The capacity and purification efficiency are significantly improved.

Moreover, since the muffler of the present invention has a high exhaust gas purification capability, it is not necessary to provide an exhaust gas purification device separately from the muffler, and the output and efficiency of the internal combustion engine are not impaired. Therefore, the exhaust gas purification process can be performed without increasing the cost, and the exhaust system can be made smaller and lighter.

[0008]

EXAMPLE An example of the present invention shown in FIGS. 1 and 2 will be described below. The main body 2 of the muffler 1 is composed of a cylindrical thin steel plate cylinder 3 and two end plates 4 and 5 crimped to both end edges of the cylinder 3, and the main body 2 has a central portion at the center thereof. A central cylindrical portion 6 oriented in the axial direction and an intermediate cylindrical portion 13 are arranged substantially concentrically on the outer periphery of the central cylindrical portion 6.

The central cylindrical portion 6 is formed by sandwiching a catalyst body 10 between an inner cylinder 8 and an outer cylinder 9 made of a thin steel plate having a large number of small holes 7. One end of the central cylindrical portion 6 is an end. It penetrates through the plate 4 and is integrally fitted to a flange 11, and a communication opening 12 is provided at the other end of the central tubular portion 6, and the flange 11 communicates with an exhaust port of an internal combustion engine (not shown). It is designed to be connected to the exhaust pipe.

Further, the intermediate tube portion 13 is also formed by sandwiching the catalyst body 17 between an inner tube 15 and an outer tube 16 made of a thin steel plate having a large number of small holes 14 similarly to the central tube portion 6. A communication opening 18 is provided at one end of the portion 13, a first chamber 19 is formed in the central tubular portion 6, and an intermediate tubular portion 13 and a central tubular portion 6 are provided.
The second chamber 20 is formed between them, and the third chamber 21 is formed by the tubular body 3 and the intermediate tubular portion 13.

Further, an exhaust opening 22 is formed at a position near the outer circumference of the end plate 5, and a tail pipe 23 is integrally fitted to the exhaust opening 22. Incidentally, the catalyst body 10, the catalyst body 17
Is a cloth made of heat-resistant fiber such as suspension wool and glass wool.
1 ₂ O ₃ is coated and a precious metal catalyst such as platinum, rhodium, rare earth metal, or cesium is supported.

Since the embodiment shown in FIGS. 1 and 2 is constructed as described above, the internal combustion engine (not shown) is started, and the exhaust gas flowing into the central tubular portion 6 from one end of the central tubular portion 6 is discharged. When flowing in the first chamber 19 toward the communication opening 12 in the direction of the central axis, it contacts the catalyst body 10 through the small hole 7 of the inner cylinder 8 in the central cylinder portion 6 to absorb sound and purify exhaust gas. Then, it flows into the second chamber 20 from the communication opening 12 and flows toward the communication opening 18, and at this time also, the catalyst body 10 is contacted through the small hole 7 of the outer cylinder 9 in the central cylinder portion 6 and Sound is absorbed and exhaust gas is purified by coming into contact with the catalyst body 17 through the small hole 14 of the inner cylinder 15 in the intermediate cylinder portion 13, and further flows into the third chamber 21 from the communication opening 18 and then to the exhaust opening 22. Flow toward the catalytic body through the small hole 14 of the outer cylinder 16 in the intermediate cylindrical portion 13 in this case as well. In contact with 17, sound absorption and exhaust gas purification are performed.

Since the sound absorption and the exhaust gas purification are carried out in three stages in this manner, the exhaust noise level is significantly reduced and the exhaust gas is sufficiently purified.

Further, since no special exhaust gas purification structure is required, the exhaust efficiency is high, the output and performance of the internal combustion engine are maintained at a high level, the cost is not increased, and the size and weight of the exhaust system can be reduced. It will be possible.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a silencer for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged perspective view of a main part thereof.

[Explanation of symbols]

1 ... Silencer, 2 ... Main body, 3 ... Cylindrical body, 4, 5 ... End plate, 6 ...
Central cylinder part, 7 ... Small hole, 8 ... Inner cylinder, 9 ... Outer cylinder, 10 ... Catalyst body, 11 ... Flange, 12 ... Communication opening, 13 ... Intermediate cylinder part, 14 ...
Small hole, 15 ... Inner cylinder, 16 ... Outer cylinder, 17 ... Catalyst body, 18 ... Communication opening, 19 ... First chamber, 20 ... Second chamber, 21 ... Third chamber, 22 ... Exhaust opening, 23 ... Tail pipe .

Claims (1)

(57) [Scope of utility model registration request] 1. A silencer main body has a substantially tubular shape, and a central tubular portion axially oriented to the central portion thereof and an intermediate tubular portion substantially concentrically provided on the outer periphery thereof are arranged. The intermediate cylinder portion is formed by sandwiching a porous catalyst between thin inner and outer cylinders having a large number of small holes, one end of the central cylinder portion is connected to an exhaust port of an internal combustion engine, and the other end of the central cylinder portion is formed. A silencer for an internal combustion engine, in which a communication opening is formed in the intermediate cylinder portion, a communication opening is formed at one end of the intermediate tubular portion, and an exhaust opening is formed at the other end of the silencer body.