JPS6238818A - Muffler for motor-cycle - Google Patents

Abstract

PURPOSE:To reduce the generation of tar mainly in a two cycle engine, by inserting a cylindrical internal cylinder into the rear portion of a muffler body and forming a hollow portion therebetween so as to make the rear portion of the muffler body in heat insulating structure. CONSTITUTION:Two partitions 4 are disposed in the center of a muffler body 1 at prescribed internal, and their circumferential cylinder portions 4a are welded to the muffler body 1. In the above construction, into the rear portion of the muffler body 1, an internal cylinder 5 which has less diameter than the body 1 is inserted, and both ends of the internal cylinder 5 are fixed by a supporting brackets 6, 7. And cylinder portions 6a, 7a, which are formed at both the above-mentioned brackets 6, 7 close both ends of the space between the muffler body 1 and the internal cylinder 5 so as to define a hollow portion 8. And a silencer (not shown in the figure) is inserted into the internal cylinder 5, and its each portion is supported by the attachment holes 4b of the partitions 4, the supporting bracket 6 and the attachment holes 9b of rear partitions 9 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a muffler for a motorcycle, and particularly to a muffler capable of reducing the amount of tar generated.

[Conventional technology]

-a. In a two-stroke engine, lubricating oil is mixed with the fuel and burned, so the exhaust gas contains a large amount of tar. Therefore, there is a problem that tar tends to accumulate in mufflers for 2-cycle engines, and various types of mufflers for 2-cycle engines that have a structure that removes tar that has accumulated inside the muffler have been proposed (for example, (Refer to Japanese Patent Publication No. 57-51906).

(Problems to be Solved by the Invention) In other words, in conventional mufflers, the generation of tar is basically unavoidable, and the problem is how to effectively remove the tar accumulated inside the muffler. Naturally, periodic tar removal work is required.

The present invention has been made in view of the conventional situation, and provides a muffler for motorcycles with a simple structure that can greatly reduce the number of tar removal operations by reducing the amount of tar generated, which is unique to two-stroke engines. is intended to provide.

Means for Solving Problem C] The present inventor has focused on the fact that in the exhaust system of a two-stroke engine, the amount of tar generated increases when the temperature of the exhaust gas falls below a certain level. To explain in detail the mechanism of tar generation in a two-stroke engine, the exhaust gas temperature in a two-stroke engine is naturally low, and in order to ensure engine performance, the primary expansion chamber is formed large, so gas expansion causes the temperature to drop further. Moreover, the temperature of the exhaust gas decreases as the distance from the engine exhaust port increases, and therefore, in a two-stroke engine, a large amount of tar is generated at the rear of the muffler. From this point of view, the inventor of the present invention came up with the idea of reducing the amount of tar generated by creating a heat-insulating structure at the rear of the muffler to prevent the exhaust gas temperature from becoming too low at the rear of the muffler. This was realized by

Therefore, the present invention provides a muffler for a motorcycle equipped with a two-stroke engine with a heat-retaining structure. That is, by inserting an inner cylinder into the rear part of the muffler body and supporting the front and rear parts of the inner cylinder on the muffler body with support brackets, a hollow part surrounded by the inner cylinder, the muffler body, and the support bracket is formed. This realizes a heat-retaining structure.

[Effect]

- As mentioned above, when the exhaust gas falls below a predetermined temperature, the amount of tar generated increases, but in the muffler according to the present invention, since a hollow part is formed at the rear of the muffler body, this hollow part Due to the heat retention effect, the temperature drop of the exhaust gas at the rear part is suppressed, and the amount of tar generated is reduced accordingly. Moreover, the above-mentioned heat retention structure is realized by a simple structure in which an inner cylinder is inserted into the muffler main body, and this is fixed to the muffler main body by a support bracket to form a hollow part.

〔Example〕

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

1 and 2 show one embodiment of the present invention.

In the figure, 30 is a two-stroke engine, and an exhaust pipe 32 of a muffler 31 of this embodiment is connected to an exhaust port 30a of the engine 30. The muffler main body 1 is connected to the rear end of the exhaust pipe 32 by a connecting fitting 2.

The front part of this muffler body 1 has a conical shape with a large diameter at the rear, and the rear part has a cylindrical shape. Moreover, two substantially disc-shaped partitions 4 are arranged at a predetermined interval in the substantially central part of the muffler main body l, and a cylindrical part 4a formed on the outer periphery of this partition is plug welded to the muffler main body 1. There is. A first expansion chamber 19 is located in front of the partition 4 at the front of the muffler main body l. Further, 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, which will be described later, through its mounting hole 4b. Note that 4C is a plurality of gas inflow holes.

An inner cylinder 5, which is a cylindrical member having a smaller diameter than the main body 1, is inserted into the rear part of the muffler main body 1. This inner cylinder 5
Support brackets 6.7 are fixed to both ends of the support bracket. A cylindrical portion 6a+7 formed on the outer periphery of the bracket 6.7.
a is 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 thereby the support brackets 6, 7. A space surrounded by the inner cylinder 5 and the muffler main body 1 is a hollow portion 8.

Furthermore, three rear partitions 9 are arranged at predetermined intervals within the inner cylinder 5, and a cylindrical part 9a formed on the outer periphery.
is plug-welded to the inner cylinder 5, whereby an expansion chamber is defined by the partition 9 and the silencer. The support bracket 6 and partition 9 also serve as support brackets that support the silencer through attachment holes 6b and 9b formed on the inner periphery.

A silencer 0 is inserted into the inner cylinder 5, and the front part of the silencer O is supported by the mounting hole 4b of the partition 4, and the central part is supported by a support bracket 6,
The silencer 0 is supported by mounting holes 6b and 9b of the rear partition 9, and the rear end of the silencer 0 is fastened to the rear end surface of the muffler body 1 by bolts 13.

This silencer 0 has a cylindrical shape, and has a punching hole 10a formed in the front part and an introduction hole 10b formed in the center part. Note that 11 and 12 are wire mesh for sound insulation.

It is glass wool.

Next, the effects of this embodiment will be explained.

In this embodiment, as shown by the arrow in FIG.
After expanding in the first expansion chamber 19 of the muffler body l,
It flows from inside the silencer 10 through the punching hole 10a to the expansion chamber 21, and further flows between the silencer 10 and the expansion chambers 22 to 2.
In this way, the exhaust gas repeatedly expands and contracts within the muffler body 1, and is discharged to the outside of the muffler body 1 while being muffled.

In this case, as the exhaust gas flows downstream, its temperature decreases due to the above-mentioned silencing and heat dissipation from the surface of the muffler body l. As mentioned above, in a two-stroke engine, the temperature of the exhaust gas is inherently low, and since the first expansion chamber 19 is large, the temperature of the exhaust gas is further lowered by expansion there. Therefore, in a muffler for a two-stroke engine, the temperature of exhaust gas tends to drop near the silencer to a temperature where tar is likely to be generated, and therefore tar is likely to accumulate in this silencer portion. On the other hand, in this embodiment, a hollow part 8 is formed at the rear of the muffler body 1, which acts as a heat insulator, thereby suppressing the temperature drop of the exhaust gas and greatly reducing the amount of tar generated. . Therefore, tar removal work can be done much less frequently than with conventional mufflers.

Further, the heat retention effect is achieved by inserting the inner cylinder 5 into the muffler body 1 to form the hollow part 8, so the structure is very simple. Furthermore, the hollow portion 8 also serves as a sound insulator, and therefore exhaust noise is also reduced.

〔Effect of the invention〕

As described above, according to the muffler for a motorcycle according to the present invention, since the rear part of the muffler body has a heat-retaining structure, it is possible to reduce the amount of tar generated.

Moreover, this heat-insulating structure can be realized by simply inserting a cylindrical member into the muffler body to form a hollow portion, which has the advantage of a very simple structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view showing the rear part of a muffler according to an embodiment of the present invention, and FIG. 2 is a side view showing the muffler of the above embodiment connected to an engine. In the figure, 1 is a muffler main body, 5 is an inner cylinder, 6.7 is a support bracket, 8 is a hollow part, 10 is a silencer, and 31 is a muffler.

Claims (1)

[Claims] (1) In a muffler for a motorcycle equipped with a two-stroke engine, a cylindrical inner cylinder is inserted into the rear of the cylindrical muffler body, and the front and rear parts of the inner cylinder are fixed to the muffler body via support brackets. A muffler for a motorcycle, characterized in that a hollow portion is formed surrounded by a muffler main body, an inner cylinder, and a support bracket, and a silencer is removably disposed within the inner cylinder.