JPS6338524B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a muffler for an exhaust system in an internal combustion engine.

In this type of muffler, there is generally a strong relationship between back pressure and silencing performance, and as back pressure is reduced, silencing performance deteriorates. In addition, from the standpoint of improving fuel efficiency and engine output, the lower the back pressure, the better. However, since it is also necessary to improve the noise reduction performance, the size of the back pressure is generally determined in consideration of the noise reduction performance. has been decided.

Conventionally, as shown in FIG.
In a muffler constructed by incorporating three partition plates 2 and three to four pipes 3, the dimensions of each are determined by finding a compromise between back pressure and noise reduction performance, but the exhaust This has the drawback that the back pressure is extremely high due to contact with the plate 2, etc., which inhibits improvements in fuel efficiency and engine output.

Therefore, an object of the present invention is to provide a muffler that allows exhaust gas to flow easily and reduces back pressure, while also not deteriorating the silencing performance. The rear end is opened inside the muffler to form a straight pipe,
Further, the exhaust inlet pipe is characterized in that the exhaust outlet pipe 8 is branched, the rear end thereof is opened to the outside of the muffler, and small holes are formed at appropriate positions in the exhaust inlet pipe and the pipe body connected thereto. It is something.

Next, an embodiment of the present invention shown in FIG. 2 will be described.

The outer peripheral wall constituting the muffler is formed by an outer cylinder 4 and front and rear walls 5, 5. Reference numeral 6 denotes an exhaust gas introduction pipe, and the pipe 6 is linearly extended rearward within the muffler to become a resonance phenomenon generating pipe 7, and its rear end 7a is opened into the muffler internal space sealed by the outer peripheral wall. . The diameter and dimensions of the resonance phenomenon generating tube 7 are set so that the Helmholtz resonance phenomenon is caused in relation to the muffler internal space. At a portion extending from the exhaust gas introduction pipe 6 to the resonance phenomenon generating pipe 7, an exhaust gas discharge pipe 8 is branched toward the rear, and its rear end is communicated with an exhaust pipe outside the muffler. Branch portion 8a of the exhaust outlet pipe 8
is formed in an arc shape so that the exhaust gas flowing in from the exhaust gas introduction pipe 6 flows to the exhaust gas discharge pipe 8 with little resistance. Incidentally, the exhaust gas introduction pipe 6, the straight pipe 7, and the exhaust gas discharge pipe 8 all use pipes having the same cross section.

Small holes 9 are provided at appropriate locations in the exhaust gas introduction pipe 6, the straight pipe 7, and the exhaust gas discharge pipe 8.

As described above, the exhaust gas from the exhaust introduction pipe 6 is discharged into the muffler internal space through the straight pipe 7 arranged in a straight line, thereby causing the Helmholtz resonance phenomenon and muffling the noise. Further, since the pressure inside the straight pipe 7 is increased by the introduced exhaust gas, the exhaust gas flowing from the exhaust gas introduction pipe 6 is guided to the branched exhaust gas outlet pipe 8 and discharged. At this time, since the exhaust outlet pipe 8 is a communicating pipe whose rear end is open to the outside of the muffler, there is little resistance to the outflow of exhaust gas, and therefore back pressure can be kept low. Furthermore, if the branch portion 8a of the exhaust outlet pipe 8 is formed into a single curve or a reciprocal curve, the above-mentioned reduction in resistance can be improved. In particular, in this invention, by providing the small hole 9 at a suitable location in the exhaust introduction pipe and the pipe body connected thereto, the exhaust pipe flowing out from the small hole into the muffler internal space causes an expansion phenomenon, and the sound pressure is attenuated and the sound is muffled. In addition, it interferes with the exhaust gas flowing out from the rear end 7a of the straight pipe, thereby muffling the noise.

As described above, according to the present invention, the back pressure can be reduced without deteriorating the silencing performance, and the fuel efficiency and output of the engine can be improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing a conventional muffler, Fig. 2 is a side sectional view showing an embodiment of the present invention, and Fig. 3 is a schematic sectional view showing a conventional muffler.
- This is a cross-sectional view taken along line B. 6...Exhaust introduction pipe, 7...straight extension pipe, 7a...open end,
8...Exhaust introduction pipe, 8a...Branch portion, 9...Small hole.

Claims (1)

[Claims] 1 Extend the exhaust introduction pipe linearly into the muffler and open the rear end into the muffler to form a straight pipe 7,
The exhaust introduction pipe has an exhaust outlet pipe 8 branched off, the rear end of which is opened to the outside of the muffler, and small holes are formed at appropriate positions in the exhaust introduction pipe and the pipe body connected thereto. A muffler for the exhaust system of an engine.