JPH0524912U - Exhaust silencer - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce exhaust noise without increasing the size of the muffler. [Structure] Punching steel wool 8 is wound around the outer circumference of an inner tube 7 having small holes 2, and glass wool 5 is filled between the punching steel wool 8 and the outer tube 3. The exhaust gas G passes through the small holes 2 and first enters the punching steel wool 8 which is excellent in sound absorption and strength, and then enters the glass wool 5 which is excellent in heat insulating property, and is silenced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention mainly relates to an exhaust silencer used in a vehicle such as a motorcycle.

[0002]

[Prior Art]

 2. Description of the Related Art Conventionally, there is an exhaust muffler for motorcycles that uses glass wool as a sound absorbing material (see Japanese Utility Model Laid-Open No. 52-149943). An example of this type of exhaust silencer is shown in FIG.

In FIG. 3, an exhaust muffler 1 is provided in an exhaust pipe 10 connected to an engine (not shown). The inner pipe 7 of the muffler 1 is provided with a large number of small holes 2. Glass wool 5 is filled between the inner tube 7 and the outer tube 3 that covers the outer circumference of the inner tube 7, that is, the expansion chamber 4. In addition, 6 is a blanking cloth. This type of muffler 1 reduces the exhaust sound level by expanding the exhaust gas and absorbing it by the glass wool 5.

[0004]

[Problems to be solved by the device]

 However, since the sound absorption by the glass wool 5 is determined by the amount of the glass wool 5, it is necessary to increase the outer diameter of the muffler 1 to reduce the exhaust noise. For example, if the muffler 1 is enlarged in a motorcycle, it is necessary to dispose the muffler 1 at the rear part of the vehicle body in order to avoid the interference between the body frame (not shown) and the muffler 1, and the center of gravity of the motorcycle is rearward. Move to. The present invention has been made in view of the above conventional problems, and an object thereof is to reduce the exhaust noise without increasing the size of the exhaust silencer.

[0005]

[Means for Solving the Problems]

 To achieve the above object, the present invention interposes punching steel wool covering the outer circumference of the inner tube between the inner tube having small holes and the glass wool.

[0006]

[Action]

 According to this invention, the sound wave of the exhaust gas is absorbed by the punching steel wheel through the small hole of the inner tube, so that the exhaust sound is reduced.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the inner tube 7 is a baffle pipe in which a punching plate is formed into a cylindrical shape, and a punching steel wool 8 is wound around the outer circumference thereof. That is, a punching steel wool 8 that covers the outer circumference of the inner tube 7 is interposed between the glass wool 5 and the inner tube 7.

FIG. 2A shows a cross-sectional view of the muffler (exhaust silencer) 1. As shown in Fig. 2 (a), the muffler 1 has a cross section having an oval shape narrow in the width direction W of the motorcycle so that the width of the motorcycle does not increase. There is. As shown in the enlarged view of FIG. 2B, the punching steel wool 8 is made of a thin fiber-like bundle of iron-based metal (wire diameter 35 μm to 55 μm). This punching steel wall 8 has a horizontal line 8a extending in the circumferential direction A of the inner pipe 7 and a vertical line 8b extending in the axial direction B (see FIG. 1) of the inner pipe 7 sandwiched from above and below by a needle punch ( It has a three-layer structure in which it is connected to each other by (not shown) and entwined with each other to be integrated, and this three-layer structure is wound around the outer circumference of the inner pipe 7 twice. The punched steel wool 8 is compressed to an extent of having a weight of 700 g to 1000 g per 1 square meter (thickness 3 mm to 5 mm). Other configurations are similar to those of the above-mentioned conventional technique, and the same portions or corresponding portions will be denoted by the same reference numerals and detailed description thereof will be omitted.

In the above structure, the exhaust gas G introduced from the exhaust pipe 10 of FIG. 1 into the muffler 1 has a sound wave passing through the small holes 2 and its energy is absorbed by the punching steel wool 8 having a large sound absorbing property. Even with the muffler 1 having the same size as the conventional one, the exhaust noise level can be lowered. For example, according to an experiment by the present inventor, the static noise level measured at a position 2 m from the rear exhaust gas angle of 45 ° dropped from 99 dB to 98 dB.

Further, in the vicinity 1a of the inlet of the muffler 1, the exhaust gas G of high temperature and high pressure first collides with the punching steel wool 8 having high strength and then hits the glass wool 5 having low strength, so that the glass wool 5 can be protected. it can. Therefore, the scattering of the glass wool 5 can be prevented, and the durability of the glass wool 5 is improved.

By the way, it is conceivable to fill the space between the inner pipe 7 and the outer pipe 3 with punching steel wool 8, but if this is done, the heat insulating property is lost and the outer pipe 3 becomes hot. It also becomes heavy in weight. On the other hand, in the present invention, the glass wool 5 is provided on the outer circumference of the punched steel wool 8 and the glass wool 5 is used as a heat insulating material, so that the outer tube 3 does not become hot.

It is also conceivable to use carbon fiber instead of punching steel wool 8. However, in the case of carbon fiber, since it is necessary to continuously wind the carbon fiber around the inner tube 7, the cost is significantly increased. On the other hand, in the case of punching steel wool 8, as described above, for example, a bundle of three layers may be wound and the cost does not increase so much.

It is also conceivable to use aluminum or brass fibers instead of the punching steel wool 8. However, fibers such as brass are easily burned by the exhaust gas G at high temperature. On the other hand, in this invention, since punching steel wool 8 having high heat resistance is used, there is no possibility of melting due to heat.

By the way, the weight per square meter (thickness: 3 mm to 5 mm) of the punched steel wool 8 is most preferably about 700 g to 1000 g. The reason is that if it is less than 700 g / square meter, the amount of punching steel wool 8 is too small to obtain a sufficient sound-deadening effect. This is because it is not so preferable in terms of effect.

The present invention can be applied to mufflers for automobiles, three-wheeled vehicles and four-wheeled vehicles, in addition to the muffler 1 for motorcycles.

[0016]

[Effect of the device]

 As described above, according to the present invention, the punching steel wool covering the outer circumference of the inner tube is inserted between the inner tube having the small hole and the glass wool, so that the exhaust sound of the punching steel wool having a large sound absorbing property is provided. The level of the exhaust muffler can be lowered, and there is no fear that the exhaust silencer will be upsized. Since punched steel wool has excellent heat resistance and mechanical properties, punched steel wool protects glass wool from high-temperature and high-pressure exhaust, which improves the durability of glass wool.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a muffler of a motorcycle according to an embodiment of the present invention.

FIG. 2A is a transverse sectional view of the same, and FIG. 2B is an enlarged sectional view of punched steel wool.

FIG. 3 is a vertical sectional view showing a muffler of a conventional motorcycle.

[Explanation of symbols]

1 ... muffler, 2 ... small hole, 3 ... outer tube, 5 ... glass wool,
7 ... inner tube, 8 ... punching steel wool.

Claims (1)

[Scope of utility model registration request] 1. An exhaust silencer in which a large number of small holes are provided on a side surface of an inner tube and glass wool is filled between the inner tube and an outer tube which covers an outer periphery of the inner tube. An exhaust silencer, in which punching steel wool covering the outer circumference of the inner pipe is inserted.