JPH0686809B2 - Motorcycle muffler - Google Patents

Description

TECHNICAL FIELD The present invention relates to a muffler for a motorcycle, and more particularly to a muffler capable of reducing the amount of tar generated.

[Conventional technology]

Generally, in a two-cycle engine, combustion is carried out in a state where fuel is mixed with lubricating oil, and therefore exhaust gas contains a large amount of tar. Therefore, a muffler for a two-cycle engine has a problem that tar easily accumulates. Conventionally, various mufflers for two-cycle engines having various structures that easily remove the tar accumulated in the muffler have been proposed (for example, JP-A-57). -51906).

[Problems to be solved by the invention]

That is, in the conventional muffler, basically, the generation of tar is unavoidable, and since it is from the viewpoint of how to easily remove the tar accumulated in the muffler, it is naturally necessary to perform regular tar removal work. is there.

The present invention has been made in view of such a conventional situation, and provides a muffler for a motorcycle having a simple structure capable of greatly reducing the number of tar removal operations by reducing the amount of tar generated peculiar to a two-cycle engine. It is intended to be removed.

[Means for solving problems]

The present inventor has paid attention to the fact that the amount of tar generated increases when the exhaust gas falls below a certain temperature in the exhaust system of a two-cycle engine. Explaining in detail the tar generation mechanism in the two-cycle engine, the exhaust gas temperature is originally low in the two-cycle engine, and the primary expansion chamber is formed large in order to secure the engine performance. In addition, the temperature of the exhaust gas decreases as the distance from the exhaust port of the engine increases, and therefore, in a two-cycle engine, the amount of tar generated at the rear of the muffler is large. From this point, the present inventor has thought that the amount of tar generated can be reduced by making the rear part of the muffler have a heat retaining structure so that the exhaust gas temperature does not become too low in the rear part of the muffler. It was realized by.

Therefore, the present invention provides a muffler for a motorcycle equipped with a two-cycle engine with a heat retaining structure. That is, the inner cylinder is inserted into the rear part of the muffler body, and the front and rear parts of the inner cylinder are supported by the support bracket on the muffler body to form an outer peripheral hollow part surrounding the outer circumference of the inner cylinder by the muffler body and the support bracket. By closing the rear end opening of the muffler body with an end plate and partitioning the portion near the rear end of the inner cylinder with a partition plate, the rear end portion of the inner cylinder is surrounded after the outer peripheral hollow portion. Form a hollow end,
A silencer is detachably disposed in the inner cylinder, and a tail cylinder connected to the rear end of the silencer is passed through the rear hollow portion to face outward, thereby realizing a heat retaining structure. is there.

[Action]

As described above, if the exhaust gas is below a predetermined temperature, the amount of tar generated increases, but in the muffler according to the present invention, an outer peripheral hollow portion and a rear end hollow portion subsequent to the hollow portion are formed in the rear portion of the muffler body. Therefore, the temperature retaining effect of the hollow portion suppresses the temperature drop of the exhaust gas in the rear portion, and the amount of tar generation is reduced accordingly. Moreover, the heat retaining structure is realized by a simple structure in which the inner cylinder is inserted into the muffler body and is fixed to the muffler body by the support bracket to form the hollow portion.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. In the figure, reference numeral 30 is a two-cycle engine, and an exhaust pipe 32 of a muffler 31 of this embodiment is connected to an exhaust port 30a of the engine 30. A muffler body 1 is connected to a rear end of the exhaust pipe 32 by a connecting fitting 2.
The front portion of the muffler body 1 has a conical shape with a larger diameter toward the rear, and the rear portion has a cylindrical shape. In addition, two substantially disk-shaped partitions 4 are arranged at a predetermined interval in the substantially center of the muffler body 1, and a cylindrical portion 4a formed on the outer periphery of the partition 4 is plug-welded to the muffler body 1. . The front part of the muffler body 1 with respect to the partition 4 is a first expansion chamber 19. The rear partition 4 defines a second expansion chamber 20 with the front partition 4 and serves as a support bracket that supports a silencer described later with its mounting hole 4b. In addition, 4c is a plurality of gas inflow holes.

An inner cylinder 5 which is a cylindrical member having a diameter smaller than that of the main body 1 is inserted in the rear portion of the main body 1 of the muffler. This inner cylinder 5
Support brackets 6 and 7 are fixed to both ends of the. The cylindrical portions 6a, 7a formed on the outer peripheral portions of the brackets 6, 7 are plug-welded to the inner surface of the muffler body 1 to close the gap between the muffler body 1 and both ends of the inner cylinder 5, and A space surrounded by the support brackets 6, 7, the inner cylinder 5, and the muffler body 1 is an outer peripheral hollow portion 8a. Further, three rear part partitions 9 are arranged in the inner cylinder 5 at a predetermined interval, and a cylindrical portion 9a formed on the outer periphery is plug-welded to the inner cylinder 5, whereby the partition 9 and the silencer are joined together. An expansion chamber is defined. The support bracket 6 and the partition 9 have mounting holes formed on the inner circumference.
It is also a support bracket that supports the silencer with 6b and 9b.

A silencer 10 is inserted in the inner cylinder 5, the front portion of the silencer 10 is supported by the mounting holes 4b of the partition 4, and the central portion thereof is supported by the support bracket 6 and the mounting holes 6b, 9b of the rear partition 9. Further, the tail cylinder 14 at the rear end of the silencer 10 is fastened and fixed by bolts 13 to the end plate 1a which is bent and formed at the rear end of the muffler body 1. As a result, the rear portion of the inner cylinder 5 is partitioned by the rear end partition 9 '(partition plate),
A rear end hollow portion 8b surrounding the rear end portion of the inner cylinder 5 is formed, and the rear end hollow portion 8b is continuous with the outer peripheral hollow portion 8a with the support bracket 7 interposed therebetween. The silencer 10 has a cylindrical shape, and has a punching hole 10a in the front part and an introduction hole 10b in the center part. In addition, 11 and 12 are a sound insulation wire mesh and glass wool, respectively.

Next, the function and effect of this embodiment will be described.

In the present embodiment, as shown by the arrow in FIG. 2, exhaust gas from the two-cycle engine 30 expands from the exhaust pipe 32 in the first expansion chamber 19 of the muffler body 1 and then from the silencer 10 to the punching hole 10a. Flow into the expansion chamber 21 through the introduction hole between the silencer 10 and the expansion chambers 22-24.
The exhaust gas circulates through 10b, and in this way, the exhaust gas repeatedly expands and contracts in the muffler body 1, and at this time, is exhausted to the outside of the muffler body 1 while muting.

In this case, the exhaust gas lowers in temperature as it flows downstream due to the noise reduction and heat dissipation from the surface of the muffler body 1. As described above, in the two-cycle engine, the temperature of the exhaust gas is originally low, and the first expansion chamber 19 is large, so that the temperature is further lowered by the expansion here. Therefore 2
In a muffler for a cycle engine, exhaust gas tends to fall to a temperature where tar is likely to be generated near the silencer, and therefore tar is likely to be accumulated in the silencer portion. On the other hand, in the present embodiment, the outer peripheral hollow portion 8a and the rear end outer peripheral portion 8b are formed in the rear portion of the muffler body 1, which serves as a heat retaining function, which suppresses the temperature drop of the exhaust gas and generates tar. The amount is greatly reduced. Therefore, the tar removal work can be performed in a very small number of times as compared with the conventional muffler.

The heat retaining effect is realized by inserting the inner cylinder 5 into the muffler body 1 to form the outer circumference and the rear end hollow portions 8a and 8b, and the structure is very simple. Moreover, the hollow portions 8a and 8b also have a sound insulating function, and therefore exhaust noise is also reduced.

〔The invention's effect〕

As described above, according to the muffler of the motorcycle of the present invention, since the rear part of the muffler body has the heat retaining structure, the amount of tar generated can be reduced. Moreover, this heat retaining structure can be realized only by inserting the tubular member into the muffler body to form the hollow portion, and there is an effect that the structure is very simple.

[Brief description of drawings]

FIG. 1 is a sectional side view showing a rear portion of a muffler according to an embodiment of the present invention, and FIG. 2 is a side view showing a state in which the muffler of the above embodiment is connected to an engine. In the figure, 1 is a muffler body, 5 is an inner cylinder, 6 and 7 are support brackets, 8a and 8b are outer peripheries, a rear end is a hollow portion, 10 is a silencer, and 31 is a muffler.

Claims (1)

[Claims] 1. In a muffler for a motorcycle equipped with a two-cycle engine, a cylindrical inner cylinder is inserted into the rear part of the cylindrical muffler body, and the front and rear parts of the inner cylinder are connected to the muffler main body via a support bracket. By fixing the muffler body and the support bracket to form an outer peripheral hollow portion surrounding the outer periphery of the inner cylinder, closing the rear end opening of the muffler body with an end plate, and partitioning the portion near the rear end of the inner cylinder with a partition plate. By forming a rear end hollow portion surrounding the rear end portion of the inner cylinder following the outer peripheral hollow portion, a silencer is detachably disposed in the inner cylinder, and the silencer is attached to the rear end of the silencer. A muffler for a motorcycle, characterized in that the connected tail tube penetrates the hollow portion at the rear end and faces the outside.