JPH0441213Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a muffler tail pipe.

[Prior art] Gas burned in the cylinder head of an engine is discharged into the atmosphere, but as it is, it has a high temperature and a loud explosion sound, so it is necessary to reduce the heat and volume before exhausting it. Therefore, as shown in FIG. 3, a muffler 4 is installed at the tip of an exhaust pipe 3 connected to an exhaust port 2 of a cylinder head 1. Muffler 4 is the first muffler at one end.
The expansion chamber 5 and the second expansion chamber 6 at the other end are connected to the gas pipe 7 at the upper part.
The second expansion chamber 6 and an intermediate third expansion chamber 8 communicate with each other through a communication port 9 at the lower part thereof, and the third expansion chamber 8 penetrates the center of the second expansion chamber 6. It is connected to the outside.

The tail pipe 10 is generally formed by attaching glass wool 12 as a sound absorbing material to the outer periphery of a thin straight punched pipe 11, and surrounding it with a straight pipe 13 fitted into the glass wool 12 as shown in the figure. As a prior art, there is Utility Model Publication No. 55-5690.

[Problem to be solved by the invention] By the way, the above tail pipe 10 has a small passage cross-sectional area for exhaust gas, and the punching pipe 11
Since the glass wool 12 is attached to the outer periphery of the exhaust gas passage, the silencing effect is sufficient, but since the exhaust resistance is large, the power is likely to be reduced.

For this reason, it is conceivable to make the punching pipe 11 thicker in order to increase the cross-sectional area of the exhaust gas passage, but if this is done, the silencing effect will be significantly reduced.

[Purpose of the invention] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a tail pipe for a muffler that has the same silencing effect as the conventional one and can increase power.

[Means for Solving the Problems] In order to solve the above problems, the muffler tail pipe according to the present invention has an inner punching pipe through which exhaust gas passes, which is gradually expanded from the outlet side toward the inlet side, and is tapered. With and without punching pipe,
A sound absorbing material is attached to the outer periphery of the tapered punching pipe, and the outer periphery is covered with a straight thick pipe.

[Function] As mentioned above, the tail pipe of the muffler according to the present invention has a tapered punching pipe in which the inner punching pipe through which exhaust gas passes gradually widens from the outlet side toward the inlet side. The cross-sectional area of the passage is large and the exhaust resistance is small. In addition, although the exhaust gas passage gradually becomes narrower toward the inlet, the exhaust gas flows smoothly along the tapered inner circumferential surface, resulting in low frictional resistance.
This can prevent power down. Furthermore, the cross-sectional area of the exit of the exhaust gas passage is small, and when the exhaust gas flows along the tapered inner circumferential surface, the exhaust noise is more efficiently absorbed by the sound-absorbing material on the outer periphery than the punched holes of the punched pipe, resulting in a sound silencing effect. It's big.

[Example] An example of the tail pipe of a muffler according to the present invention will be described with reference to FIG. Since the same reference numerals in the figure as in FIG. 3 indicate the same parts, the explanation thereof will be omitted. 1
Reference numeral 5 designates a tail pipe, which is an inner punching pipe through which exhaust gas passes, which is gradually expanded from the outlet side toward the inlet side to form a punching pipe 17 with a taper 16. In this example, the outlet diameter is 25 mm, the inlet diameter is 31.8 mm, the length is 250 mm, and the angle of the taper 16 is 1.6 mm.
The punch holes 18 have a diameter of 2 mm and are arranged in a staggered manner at intervals of 5 mm. Glass wool 19 with an outer diameter of 50 mm is attached to the outer periphery of the punched pipe 17 with a taper 16 as a sound absorbing material over the entire length, and the thickness on the inlet side is 8 mm and the thickness on the outlet side is 11.5 mm.
It is becoming. A straight pipe 20 is fitted onto the outer peripheral surface of this glass wool 19, and both front and rear end surfaces are covered with end plates 21, 22 of the pipe 20, and the inner peripheral edges of the end plates 21, 22 are connected to punched pipes with a taper 16. It is welded to the front and rear ends of glass wool 17 to cover the outer surface of glass wool 19.

Tail pipe 15' of another embodiment shown in FIG.
In this example, glass wool 19 is attached to the outer periphery of a punched pipe 17 with a taper 16 to a thickness of 8 mm over the entire length, and an air layer 2 is created between it and the outer pipe 20.
3 was formed.

Tail pipe 1 as shown in each of the above embodiments
The punching pipes on the inside of 5 and 15' gradually widen from the outlet side to the inlet side to form a punching pipe 17 with a taper 16, so the cross-sectional area of the exhaust gas passage is large and the exhaust resistance is small. Moreover, since the exhaust gas flows smoothly along the taper 16, the frictional resistance is small and power down can be prevented.
When the exhaust gas flows along the groove 6, the exhaust noise is efficiently absorbed by the glass wool 19 on the outer periphery through the punched hole 18, so that the noise reduction effect is large.

[Effects of the invention] As can be seen from the above explanation, the muffler tail pipe according to the invention has a large cross-sectional area for the exhaust gas passage and low exhaust resistance, and also has low frictional resistance of the exhaust gas, making it possible to prevent power loss. performance is improved. Furthermore, since the exhaust sound is more efficiently absorbed by the sound absorbing material than by the punched holes, even if the cross-sectional area of the exhaust gas passage is large, there is a noise reduction effect equal to or greater than that of the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing one embodiment of the tail pipe of a muffler according to the present invention, Fig. 2 is a longitudinal sectional view showing another embodiment, and Fig. 3 is a longitudinal sectional view showing the tail pipe of a conventional muffler. It is. 15, 15'...Tail pipe, 16...Taper, 17...Punching pipe, 18...Punching hole, 19...Glass wool, 20...Pipe, 2
1, 22... End plate, 23... Air layer.

Claims (1)

[Scope of utility model registration request] In the tail pipe of a muffler, the inner punching pipe through which exhaust gas passes gradually expands from the outlet side to the inlet side to form a tapered punching pipe, and a sound-absorbing material is attached to the outer periphery of the tapered punching pipe. The tail pipe of the muffler is made by covering the outer periphery with a straight thick pipe.