JPH068251Y2 - Exhaust silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an exhaust silencer arranged in an exhaust passage of an engine.

(Prior Art) Generally, in an engine equipped with a pressure wave supercharger, there is a demand to muffle high-frequency exhaust noise generated by the pressure wave supercharger. The high-frequency exhaust sound has a high sound pressure level in the range of 1 to 2 kHz and in the range of 6 to 8 kHz.

By the way, it is known that an exhaust silencer using a sound absorbing material is effective for silencing high-frequency exhaust noise.

However, since an exhaust silencer using a sound absorbing material usually has a structure in which a sound absorbing material is installed around an exhaust pipe having a plurality of openings, in the case of a diesel engine where smoke is likely to occur, The holes become clogged with carbon, and the sound deadening effect decreases over time. 6 ~
The sound deadening effect does not decrease so much in the range of 8 kHz, but the sound deadening effect largely decreases in the range of 1 to 2 kHz.

Further, as an exhaust silencer, one using a resonance chamber is known in addition to one using a sound absorbing material, and it is conceivable to use this. According to this, the effect of the clogging by carbon is not so great, and the sound deadening effect is obtained in the range of 1 to 2 kHz, but it is difficult to resonate in the range of 6 to 8 kHz. Is inferior.

Therefore, as disclosed in Japanese Utility Model Laid-Open No. 61-59819, it has been proposed to combine a sound absorbing material and a resonance chamber in an exhaust silencer to utilize their advantages.

(Problems to be Solved by the Invention) However, in the silencer described in Japanese Utility Model Laid-Open No. 61-59819, the partition member forming the resonance chamber is arranged so as to be orthogonal to the exhaust flow direction, and the exhaust The gas flow is configured to collide with each other, and as a result, the exhaust resistance is increased, so that it cannot be applied to the one provided with the pressure wave supercharger in which the pressure balance of the intake and exhaust pressures is important.

The present invention has been made in view of the above points, and an object of the present invention is to provide an exhaust silencer capable of silencing by combining a sound absorbing material and a resonance chamber without increasing exhaust resistance.

(Means for Solving the Problems) The present invention is an exhaust silencer arranged in an exhaust passage of an engine, which forms a hollow casing and a plurality of resonance chambers partitioning the inside of the casing in the exhaust gas flow direction. Partition member, a straight perforated pipe penetrating the casing and the partition member and having a plurality of openings in the peripheral wall and through which exhaust gas flows, and a sound absorbing member installed in a predetermined range on the outer peripheral portion of the perforated pipe. And a material.

(Operation) Exhaust gas flows through the inside of the straight perforated pipe having a plurality of openings in the peripheral wall and penetrating the casing and the partition member, so that the exhaust resistance does not increase and a plurality of holes are formed through the perforated wall in the peripheral wall. The sound of 1 to 2 kHz is muted in the resonance chamber of the sound absorber and the sound of 6 to 8 kHz is muted in the sound absorbing material.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2 showing the overall structure of an engine exhaust silencer A, 1 is a hollow cylindrical casing that is long in the up-down direction and short in the left-right direction, the inside of which is an axis line that matches the exhaust gas flow direction S. In an annular resonance chamber 3 that is partitioned by a plurality of annular partition members 2 that are arranged in parallel in a direction.
A plurality of A, 3B, 3C, 3D, 3E, 3F and 3G are formed in the exhaust gas flow direction.

Each partition member 2 is composed of an annular substrate portion 2a and inner and outer flange portions 2b and 2c that are bent in the same direction from the inner and outer peripheral edges of the substrate portion 2a. Is arranged so that its volume is small, and accordingly, high frequency sound is silenced.

Reference numeral 4 denotes a straight perforated pipe through which exhaust gas flows, a plurality of openings (only a part of which are shown) are opened in the peripheral wall thereof, and a sound absorbing material 5 is installed in a predetermined range on the outer peripheral surface. The perforated pipe 4 provided with the sound absorbing material 5 passes through the center hole formed by the inner flange portion 2b of the partition member 2 and the casing 1
Penetrates inside. The perforated pipe 4 is eccentric downward with respect to the casing 1. The inner peripheral edge of the partition member 2 may be inserted into the sound absorbing material 5.

As shown in FIG. 2, the sound absorbing material 5 is installed in the lower half of the perforated pipe 4 over the entire exhaust gas flow direction, and is in contact with the perforated pipe 4 and has a high heat resistance and vibration resistance. For example, SUS wool) and fibers 7 (for example, basalt wool) located on the outside thereof and having a high sound absorbing effect are laminated.

Further, in the perforated pipe 4, long holes 4b that are long in the exhaust gas flow direction S are regularly formed in the portion where the sound absorbing material 5 is installed, and in the other portions, as shown in FIG. As shown in FIG. 4, circular holes 4a are formed at equal intervals, and the inside of the casing 1 and the resonance chambers 3A to 3G are formed through the circular holes 4a.
And are in direct communication with each other.

The round hole 4a needs to have a diameter equal to or larger than a predetermined value (for example, 6 to 10 mm) from the viewpoint of preventing whistling noise and clogging. Further, the portion provided with the sound absorbing material 5 may be a round hole instead of the long hole 4b.

According to the above structure, the exhaust gas flows through the straight porous tube 4, and the sound deadening performance can be ensured with the structure having low exhaust resistance. Therefore, it can be applied to an engine having a pressure wave supercharger in which the pressure balance of intake and exhaust pressures is important.

Further, since the sound absorbing material 5 and the resonance chambers 3A to 3G are used in combination, the sound absorbing material 5 that does not affect the sound absorbing performance even if carbon is adhered is used for sound absorbing at 6 to 8 kHz.
The muffling of z can be performed by the resonance chambers 3A to 3G.

Therefore, it can also be applied to a diesel engine that produces smoke.

As shown in FIG. 5, an exhaust silencer B having the same structure as the exhaust silencer A may be provided in the exhaust passage 11 in series with the exhaust silencer A, and the exhaust silencer B is provided only in the resonance chamber. You may do it.

In the above-described embodiment, the resonance chambers 3A to 3G are formed in an annular shape, but a sound absorbing material may be provided in the entire lower half of the casing 1 so that only the upper half serves as the resonance chamber, or the sound absorbing material is exhausted. It may not be provided over the entire gas flow direction, but may be provided only in a part in the exhaust gas flow direction.

(Effect of the Invention) As described above, the present invention allows the exhaust gas to flow through the inside of the straight perforated pipe having the plurality of openings in the peripheral wall and penetrating the casing and the partition member, so that the exhaust resistance is improved. Also, through the holes in the peripheral wall of the perforated pipe, a sound of 1 to 2 kHz is generated in a plurality of resonance chambers and a sound absorbing material is 6 to 8 kHz.
The sound of each is silenced, and a superior silencing effect is obtained as a whole.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a sectional view showing the overall structure of an exhaust silencer of an engine, Fig. 2 is a sectional view taken along the line II-II of Fig. 1, and Fig. 3 is a sound absorption of a perforated pipe. FIG. 4 is a detailed view of a portion provided with a material, FIG. 4 is a detailed view of a portion of the perforated pipe where no sound absorbing material is provided, and FIG. 5 is a diagram of an example of an exhaust system including an exhaust silencer. A ... Exhaust silencer, 1 ... Casing, 2 ... Partition member, 3A, 3B, 3C, 3D, 3E, 3F, 3G ...
... Resonance chamber, 4 ... Perforated tube, 4a ... Long hole, 4b ... Round hole, 5 ... Sound absorbing material

Claims (1)

[Scope of utility model registration request] 1. An exhaust silencer arranged in an exhaust passage of an engine, which is a hollow casing, a partition member for partitioning the inside of the casing to form a plurality of resonance chambers in the exhaust gas flow direction, the casing, A straight porous tube having a plurality of openings in the peripheral wall and penetrating the partition member and through which exhaust gas flows, and a sound absorbing material installed in a predetermined range on the outer peripheral portion of the porous tube. A featured exhaust silencer.