JP2737079B2 - Two-stroke engine muffler - Google Patents

Description

The present invention relates to an improvement in a muffler of a two-stroke engine mounted on a motorcycle or the like.

[Conventional technology and its problems]

In a two-stroke engine, the rear end of an exhaust pipe connected to an exhaust hole of the engine is connected to a muffler so that noise of exhaust gas is muted by the muffler and emitted. In a two-stroke engine, exhaust and scavenging are performed simultaneously, and after explosive high-pressure exhaust gas flows into the exhaust holes, the exhaust gas remaining in the cylinder is extruded into the exhaust holes by injection of the scavenging gas to perform scavenging. Fill into cylinder. At this time, blow-by occurs in which a part of the scavenging air flows into the exhaust hole together with the exhaust. In order to reduce this blow-by, the exhaust pulsation wave that is intermittently exhausted is effectively used by the exhaust pipe length and the volume of the first expansion chamber in front of the muffler, and the reflected wave is used to exhaust immediately before the exhaust hole closes. By increasing the pressure near the holes, the blow-by gas is pushed back into the cylinder, the scavenging charge efficiency is increased, and the output is increased. However, since the frequency of the exhaust pulsation wave changes with the change of the rotation speed, the output of the entire rotation cannot be increased, and a portion where the output has a valley occurs. In order to prevent this, as shown in FIG. 6, a connecting pipe D having a diffuser pipe C welded to a rear end thereof is inserted into a first expansion chamber B at a front portion of a muffler cylinder A and welded. D is provided with an adjustment hole E for interference, and at the tip of the connecting pipe D,
The rear end of the exhaust pipe F is connected and fastened. By adjusting the length from the exhaust pipe F to the diffuser pipe C and the volume of the first expansion chamber B, the exhaust pulsation wave can be effectively used in the rotation range where high output is desired. In this case, a portion where an output valley is formed due to the interference caused by the interference is corrected. For example, see Japanese Utility Model Laid-Open No. 57-204421. By the way, in a two-stroke engine, lubricating oil is mixed into fuel to lubricate. Lubricating oil is contained in the exhaust gas, which flows in the form of tar, and is further converted into carbon-like by heat of the exhaust gas. Solidifies and adheres. In particular, there is an inconvenience that the small adjustment hole E does not function because the small adjustment hole E adheres and is blocked. Although cleaning is performed by appropriately removing the exhaust pipe F, the adjustment hole E is deep from the entrance of the connecting pipe D, and there is a disadvantage that it is difficult to remove carbon.

[Object of the invention]

According to the present invention, the rear part of the exhaust pipe provided with the adjustment hole at the rear part is inserted into the first expansion chamber of the muffler cylinder, the rear end of the exhaust pipe is connected to the diffuser pipe provided in the first expansion chamber, and the exhaust pipe is disassembled. Then, an object of the present invention is to obtain a muffler of a two-stroke engine that can easily clean an adjustment hole and recover output.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a diffuser pipe 4 which is concentrically inserted and fixed by a holding piece 3 having an opening 3a in a first expansion chamber 2 on the front side of a muffler cylinder 1. Expand the front end of the
And a connecting member 5 is integrally fixed to a front end of the muffler cylinder 1, and a rear part of an exhaust pipe 6 connecting a front part to an exhaust port of a two-stroke engine is connected to a first expansion chamber of the muffler cylinder 1. 2 and fitted into the front curl portion 4a of the diffuser pipe 4 and a packing 9 is interposed between the connection fitting 5 and the ring nut 8 so that the ring nut 8
Is fastened to the connection fitting 5 to connect the muffler cylinder 1 and the exhaust pipe 6, and substantially between the curl portion 4 a of the exhaust pipe 6 inserted into the first expansion chamber 2 and the connection fitting 5. The muffler of the two-stroke engine is characterized in that an adjustment hole 7 is formed in the center.

〔Example〕

Hereinafter, the present invention will be described with reference to the embodiments shown in FIGS.

In the muffler of the two-stroke engine according to the embodiment, the diffuser pipe 4 is coaxially inserted and fixed by the holding piece 3 having the opening 3a in the first expansion chamber 2 at the front (front side) of the muffler cylinder 1. I do. The diffuser pipe 4 has a curled portion 4a formed by expanding the front end on the upstream side outward, and
It has a tapered shape as a whole.

Then, the connecting fitting 5 is integrally fixed to the front end of the muffler cylinder 1.

An exhaust pipe 6 having a front portion connected to an exhaust port of the two-stroke engine has a length such that a rear portion can be inserted deeply into the first expansion chamber 2 of the muffler cylinder 1 and inserted into the first expansion chamber 2. An adjustment hole 7 was formed in the exhaust pipe 6 at a substantially central portion between the curl portion 4a and the connection fitting 5. The rear portion of the exhaust pipe 6 is inserted into the first expansion chamber 2 and fitted to the front curl portion 4a of the diffuser pipe 4. At the same time, a seal 9 is interposed between the connection fitting 5 and the ring nut 8 for sealing, and the ring nut 8 is fastened to the connection fitting 5 to connect the muffler cylinder 1 and the exhaust pipe 6.

 Next, the operation of the embodiment will be described.

The length of the exhaust pipe 6, the volume of the first expansion chamber 2 of the diffuser pipe 4, and the like are set so that a pulsation wave in a rotation range in which a high output is desired is effective. The portion where the output valley is formed is covered by setting the position and size of the adjustment hole 7. Although the adjustment hole 7 may be blocked by depositing carbon, the exhaust pipe 6
Can be removed by removing the ring nut 8, so that cleaning can be easily performed, carbon can be removed, and output can be restored.

〔The invention's effect〕

As described above, according to the present invention, the diffuser pipe is fixed concentrically in the first expansion chamber at the front of the muffler cylinder,
The rear end of the exhaust pipe is inserted into the first expansion chamber from the front end of the muffler cylinder, the rear end is fitted to the front part of the diffuser pipe, and an adjustment hole is provided in the insertion part of the exhaust pipe in the muffler cylinder. Even if carbon is deposited and closed, the exhaust pipe can be easily removed by removing the exhaust pipe, and the output can be restored. Further, even if there is a slight error in the length of the exhaust pipe, the exhaust pipe can be assembled and the assembly can be easily performed. Further, since the exhaust pipe can be removed, cleaning of the first expansion chamber of the muffler cylinder is also simplified.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is an exploded perspective view, FIG. 2 is a longitudinal sectional view of a main part, and FIG. 3 is an enlarged view of a part indicated by an arrow X in FIG. FIG. 4 is an enlarged view of a portion indicated by an arrow Y in FIG. 2, FIG. 5 is a transverse cross-sectional view as viewed from an arrow Z in FIG. 4, and FIG. 1 ... muffler cylinder, 2 ... first expansion chamber, 4 ... diffuser pipe, 6 ... exhaust pipe, 7 ... adjustment hole.

Claims (1)

(57) [Claims] 1. A first expansion chamber (2) on the front side of a muffler cylinder (1).
A diffuser pipe (4) is inserted and fixed concentrically with a holding piece (3) having an opening hole (3a) therein, and the upstream front end of the diffuser pipe (4) is expanded outward to curl the part (4a). ) And a connecting fitting (5) is integrally fixed to the front end of the muffler cylinder (1), and the rear part of an exhaust pipe (6) connecting the front part to the exhaust port of a two-stroke engine is connected to the muffler cylinder. First expansion chamber (2) of cylinder (1)
To be fitted into the front curl portion (4a) of the diffuser pipe (4), and a packing (9) is interposed between the connecting metal fitting (5) and the ring nut (8). The muffler cylinder (1) and the exhaust pipe (6) are connected by fastening the (8) to the connection fitting (5), and the exhaust pipe (6) inserted into the first expansion chamber (2). A muffler for a two-stroke engine, characterized in that an adjustment hole (7) is formed substantially at the center between the curl portion (4a) and the connection fitting (5).