JPS5939135Y2 - Exhaust pipe of internal combustion engine in two-wheeled vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust pipe for an internal combustion engine, and more particularly to an exhaust pipe configured in a double pipe shape with an annular hollow portion.

Conventionally, the outer surface of the exhaust pipe of an internal combustion engine, for example, the exhaust pipe of a two-wheeled vehicle, has often been plated to improve its appearance.

Since this outer surface discolors when overheated, in the prior art, the exhaust pipe is configured in a double-tube shape with an outer pipe and an inner pipe, so that the annular hollow part has a heat insulating effect.

However, if the diameter of the outer pipe is made larger, it is necessary to modify the cylinder head of the internal combustion engine to which the exhaust pipe is connected, and if the inner pipe is made smaller in diameter, the performance of the internal combustion engine will deteriorate. , it is not possible to increase the thickness of the hollow portion.

Therefore, the insulation effect of the hollow part cannot be said to be excellent.
The outer surface of the outer tube is prone to discoloration.

Furthermore, if unburned components such as O hydrocarbons in exhaust gas are secondary-combusted to prevent environmental pollution, it is necessary to maintain a high temperature inside the inner tube, making it even more difficult to suppress the temperature rise in the outer tube. becomes.

Therefore, an object of the present invention is to provide an exhaust pipe that can lower the outer surface temperature of the exhaust pipe and maintain a relatively high temperature inside the exhaust pipe.

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

The drawing is a sectional view of an embodiment of the present invention.

This exhaust pipe 1 is made up of an inner pipe 2 and an outer pipe 3 arranged in a concentric double pipe shape, and is curved to connect an engine 4 and a muffler 5 of a two-wheeled vehicle.

The outer surface of the outer tube 3 is plated to improve its appearance.

The high temperature exhaust gas discharged from the engine 4 is transported to the exhaust pipe 1
After secondary combustion of unburned substances such as hydrocarbons occurs in the inner pipe 2 of the
It is discharged through a silencer 5.

At the end of the exhaust pipe 1 on the engine 4 side (upper part of the drawing), the outer pipe 3 is provided with a connecting flange 6 to the engine 4.

The inner tube 2 is provided with a flange 7 having the same outer diameter and which is to be integrally integrated with the connecting flange 6 in a gas-tight manner.

At the end of the exhaust pipe 1 on the muffler 5 side (lower part of the drawing),
The end 2a of the inner tube 2 is hermetically fixed to the inner peripheral wall of the outer tube 3 by welding.

In this way, the annular hollow portion 8 between the inner tube 2 and the outer tube 3 is hermetically sealed.

The hollow portion 8 is filled with a heat-insulating ceramic 9 in the form of powder and having excellent heat resistance.

Therefore, the inner tube 2 through which high-temperature exhaust gas flows is surrounded by the ceramic 9, and heat transfer between the inner tube 2 and the outer tube 3 is suppressed.

Therefore, the inside of the inner tube 2 is kept at a relatively high temperature, promoting secondary combustion of hydrocarbons in the exhaust gas, preventing air pollution, and preventing the outer tube 3 from being overheated. , the plated outer surface of the outer tube 3 will not change color.

Next, a procedure for manufacturing the curved exhaust pipe 1 will be explained.

(1) First, a straight inner tube 2 and an outer tube 3 to which flanges 6.7 are fixed are prepared in advance, and the inner tube 2 is concentrically inserted into the outer tube 3 with the flanges 6.7 aligned.

In this state, the inner tube 2 and the outer tube 3 are supported vertically with the flange 6.degree. 7 facing down, and then the ceramic 9 is filled into the hollow portion 8 from the end 2a side of the inner tube 2.

At this time, since the ceramic 9 is in the form of powder, it can be easily filled.

(2) After filling the passage T with the ceramic 9, the end 2a of the inner tube 2 is welded all around the inner peripheral wall of the outer tube 3, and the hollow part 8 is hermetically closed.

(3) Bend the exhaust pipe 1 while the hollow part 8 is filled with the ceramic 9.

In this bending process, a metal core is mounted inside the inner tube 2 using a conventional method, and the core metal is bent using a bender.

During this bending process, since the hollow part 3 is filled with ceramic □tsuk 9, the inner tube 2 and the outer tube 3 are kept concentric, and the hollow part 8 is kept in an annular shape 11 instead of an axial housing. .

In the conventional example, in order to prevent the hollow part 8 from being crushed when bending the exhaust pipe 1, a low melting alloy is poured into the hollow part 8, the alloy is solidified, and then the bending process is performed, and the alloy is taken out after the bending process. There is.

According to the present invention, since the ceramic 9 is sealed in the hollow part 8, the manufacturing process is shortened.

(4) After the bending process is completed, the outer surface of the outer pipe 3 is plated to complete the manufacturing process of the exhaust pipe 1.

In addition, during the above-mentioned bending process of the exhaust pipe 1, the powder-like ceramic 9 filled in the hollow part 8 is crushed and the particle size becomes small, so that the packing density of the ceramic 9 is reduced to the extent that the heat insulation property is improved. Therefore, the heat insulating effect of the ceramic 9 is further improved.

As mentioned above, according to the present invention, the inner tube is arranged concentrically within the outer tube, and the powdery ceramic is hermetically sealed in the hollow space between the outer tube and the inner tube, so that the heat between the inner tube and the outer tube is reduced. Transmission is suppressed by the ceramic.

This prevents the outer tube from overheating and, if the surface of the outer tube is plated, prevents the surface from discoloring.

Furthermore, the inside of the inner tube can be maintained at a relatively high temperature, and therefore the secondary combustion of unburned components such as hydrocarbons in the exhaust gas can be promoted.

Since ceramic is in the form of powder, it is easy to fill the hollow space.

Furthermore, by bending the exhaust pipe after sealing the ceramic into the hollow part, there is no need to fill the hollow part with low melting alloy, sand, etc. as in the conventional method, and the manufacturing process can be shortened.

Furthermore, during the bending process of the exhaust pipe, the ceramic is crushed and the packing density is increased to the extent that the insulation properties are improved, thereby improving the insulation effect.

In particular, in the present invention, the end portion 2a of the inner tube 2 is airtightly fixed to the entire circumference of the inner peripheral wall of the outer tube 3 by welding, so that the powdery ceramic 9 in the hollow portion 8 is prevented from being discharged. At the same time, when the present exhaust pipe is bent with a bender or the like, the ceramic □tsuku 9 is crushed and the particle size can be surely reduced.

This increases the packing density of the ceramic 9, thereby further improving the heat insulating effect of the ceramic 9.

The end 2a of the inner tube 2 is also located inside the tube axis (left side in the drawing) 1
Since the outer tube 3 is fitted into the muffler 5, even if the outer surface of the outer tube 3 discolors due to heat due to the smell being closer to the outside of the tube axis (to the right in the drawing) than the end 2a, the discolored portion is silencer 5
Since it is inside, the beauty is not inferior.

In this way, discoloration due to temperature of the exhaust pipe, which is necessary for a two-wheeled vehicle to have an excellent appearance, is prevented, and the commercial value of the two-wheeled vehicle is improved.

[Brief explanation of drawings]

The drawing is a sectional view of an embodiment of the present invention. 1...Exhaust pipe, 2...Inner pipe, 3...Outer pipe, 8...
・Hollow part, 9...Ceramic.

Claims (1)

[Scope of utility model registration request] The inner tube 2 is arranged concentrically within the outer tube 3, and one end of the outer tube 3 is provided with a connecting flange 6 to the internal combustion engine 4, and the inner tube 2 is airtightly integrated with the connecting flange 6. A flange 7 having the same outer diameter is provided, and the free end 2a of the inner tube 2 is airtightly fixed to the entire circumference of the inner peripheral wall near the other end of the outer tube 3 by welding, so that the inner tube 2 and the outer tube 3 are mutually connected. Powdered ceramic 9 is filled in the annular hollow part 8 between the ends 2a of the inner tube 2.
2, characterized in that the outer tube 3 fits into the muffler 5 on the inner side 1 of the tube axis, and the outer peripheral surface of the outer tube 3 is plated.
Exhaust pipes of internal combustion engines in wheeled vehicles.