JPH0519519U - Silencer for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] To provide a silencer for an internal combustion engine having a simple structure having an exhaust gas purification function. [Structure] End plates 4 and 5 are crimped to both end edges of a cylindrical body 3 to form a main body 2, and an inner cylinder 8 and an outer cylinder 9 having a large number of small holes 7 are formed in a central portion of the main body 2 to form a catalyst body 10. A central tubular portion 6 formed by sandwiching the central tubular portion 6 and an intermediate tubular portion 13 having the same configuration as the central tubular portion 6 are provided on the outer periphery thereof, and a communication opening 12 is provided at the other end of the central tubular portion 6. Along with this, a communication opening is provided at one end of the intermediate tubular portion 13.
18 are provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 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]

[Prior Art and Problems to be Solved]

 In many conventional internal combustion engines, a monolith-type exhaust gas purification device is installed upstream of the exhaust gas passage and a silencer is installed 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 gas inertia effect cannot be derived, and the flow resistance of the exhaust gas purifying device prevents the exhaust port. Since the back pressure tends to be high and the cost is high, in a small internal combustion engine mounted on a motorcycle, the exhaust port and the silencer are connected as described in JP-A-2-221623. A catalyst was installed on the inner surface of the exhaust pipe. Although the catalyst is stretched on the inner peripheral surface of the exhaust pipe, the exhaust inertia effect can be extracted to improve the output and efficiency, but the structure is also complicated and the cost cannot be avoided.

[0003]

[Means and Actions for Solving the Problems]

 The present invention relates to an improvement of an exhaust system of an internal combustion engine which overcomes such difficulties, and a silencer body has a substantially cylindrical shape, and a central cylindrical portion axially oriented to the central portion thereof and a substantially concentric outer periphery thereof. And an intermediate tubular portion, and the central tubular portion and the intermediate tubular portion are formed by sandwiching a porous catalyst between thin inner and outer tubular tubes having a large number of small holes, and one end of the central tubular portion is It is connected to an exhaust port of an internal combustion engine, a communication opening is formed at the other end of the central cylinder portion, a communication opening is formed at one end of the intermediate cylinder portion, and an exhaust opening is formed at the other end side of the silencer body. It is characterized by being formed.

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

As described above, in the present invention, the exhaust gas has a meandering flow passage extending from the central portion to the outer peripheral portion, the throttling effect of the communication opening, and the inner and outer cylinders of the central tubular portion and the intermediate tubular portion. The exhaust noise level is significantly reduced by the effect of absorbing pressure fluctuations from the small holes to the catalyst.

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 capacity, 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. Not only can the exhaust gas be purified without increasing the cost, but the exhaust system can be made smaller and lighter.

[0008]

【Example】

 Hereinafter, an embodiment of the present invention shown in FIGS. 1 and 2 will be described. 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 tubular portion 6 oriented in the axial direction and an intermediate tubular portion 13 arranged substantially concentrically on the outer periphery thereof are arranged.

The central tubular portion 6 is formed by sandwiching a touch medium 10 between an inner tubular member 8 and an outer tubular member 9 made of a thin steel plate having a large number of small holes 7, and one end portion of the central tubular 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, similarly to the central tubular portion 6, the intermediate tubular portion 13 is also formed by sandwiching a catalyst body 17 between an inner tubular member 15 and an outer tubular member 16 made of a thin steel plate having a large number of small holes 14, 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 a second chamber 20 is formed between the intermediate tubular portion 13 and the central tubular portion 6. In addition, the cylindrical body 3 and the intermediate cylindrical portion 13 form a third chamber 21.

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. The catalyst body 10 and the catalyst body 17 are formed by coating Al ₂ O ₃ on a cloth made of heat-resistant fiber such as sauswool and glass wool, and carrying a precious metal catalyst such as platinum, rhodium, rare earth metal, and cesium. There is.

Since the embodiment of FIGS. 1 and 2 is configured 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 part 6 to absorb sound and exhaust gas. After being purified, it flows into the second chamber 20 from the communication opening 12 and flows toward the communication opening 18, and at this time also, it contacts the catalyst body 10 through the small hole 7 of the outer cylinder 9 in the central cylinder portion 6. At the same time, it contacts the catalyst body 17 through the small hole 14 of the inner cylinder 15 in the intermediate cylinder part 13 to perform sound absorption and exhaust gas purification, and further flows into the third chamber 21 from the communication opening 18, and then to the exhaust opening. Flow toward the pipe 22, again in this case through the small hole 14 in the outer cylinder 16 of the intermediate cylinder 13. In contact with the catalytic body 17, sound absorption and exhaust gas purification is performed.

As described above, since the sound absorption and the exhaust gas purification are performed in three stages, 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 exhaust system is small and lightweight. Is 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)

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