JP2015206314A - Exhaust noise muffling structure for fuel cell vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust noise muffling structure for a fuel cell vehicle, capable of effectively improving a muffling performance under the environment where an exhaust gas contains water vapor.SOLUTION: An exhaust noise muffling structure for a fuel cell vehicle is provided, in which: an expansion chamber 7 is provided in a part of an exhaust gas flow direction F of a linear part 5a of an exhaust pipe flow passage 5, which expands on the upper side than a lower end 5a1 of the linear part 5a and the outer peripheral side of the linear part 5a; the expansion chamber 7 is partitioned into two regions, which are a resonant chamber 13 on the inner peripheral side and a sound-absorbing chamber 15 on the outer peripheral side, by a partition wall having a number of through-holes 11a; the resonance chamber 13 has partition members 17 arranged therein, for partitioning an inner space thereof into a plurality of chambers which form a plurality of resonance mufflers 19 having different resonance frequencies; a sound-absorbing member 15a is filled inside the sound-absorbing chamber 15; an opening portion 19a of the resonance mufflers 19 are positioned on the outer peripheral side than a diameter of the linear part 5a; and an outer peripheral side end 10a1 of a joint R part 10a between an exhaust pipe downstream side portion 3a and an expansion chamber structural wall 9, is positioned on the outer peripheral side than the opening portion 19a.

Description

  The present invention relates to a silencer structure for reducing exhaust noise of a fuel cell vehicle.

There is a sound absorption type silencer as a kind of silencer for reducing exhaust noise of an internal combustion engine type vehicle equipped with a gasoline engine or a diesel engine. The sound absorbing silencer has an outer cylinder member that is externally fixed to a predetermined part of an exhaust pipe having a large number of through holes, and a sound absorbing material such as glass wool between the outer cylinder member and the exhaust pipe. Is a filled structure.
In recent years, sound absorbing silencers have also been applied to automobiles (fuel cell automobiles) that use fuel cells, which are expected as next-generation automobiles, as drive sources. However, problems that did not occur in the internal combustion engine type automobile are caused.

  In a fuel cell vehicle, water vapor generated during power generation is discharged as exhaust gas through an exhaust pipe, but a part of this water vapor is stored in the silencer by condensation. Therefore, the sound absorbing material such as glass wool contains water, and the sound deadening performance is significantly lowered.

In order to solve this problem, the following means are provided.
(A) Japanese Patent Application Laid-Open No. 2004-156555 (Suppression of water content of sound absorbing material)
Adjusting the sound absorbing material to a predetermined bulk density or applying water repellent treatment improves drainage, and drains water that has permeated through the sound absorbing material from the drain hole provided in the silencer housing to the outside of the silencer. Configuration.
(B) Japanese Patent Application Laid-Open No. 2002-206413 (Suppression of moisture content of sound absorbing material)
The inner space of the silencer is partitioned by a partition plate into an upper sound absorbing chamber filled with a sound absorbing material and a lower expansion chamber, an exhaust gas inlet is provided in the sound absorbing chamber, and a gas outlet is provided in the expansion chamber. Is provided with a communication hole for communicating the upper sound absorbing chamber and the lower expansion chamber.
(C) Japanese Patent Laid-Open No. 2006-200369 (no sound absorbing material is used)
A configuration in which a plurality of side branches having different resonance frequencies are provided on the outer periphery of the exhaust pipe.

However, the muffler structure disclosed in the above publication has the following problems.
(A) Japanese Patent Application Laid-Open No. 2004-156555 (Suppression of water content of sound absorbing material)
The silencer is provided at a predetermined position (mostly under the vehicle floor) of the exhaust pipe. Therefore, unlike the exhaust gas outlet, water (liquid) drips from a position where it cannot be seen, and there is a possibility that the user may feel anxiety associated with a vehicle failure.
(B) Japanese Patent Application Laid-Open No. 2002-206413 (Suppression of moisture content of sound absorbing material)
Since the exhaust gas is discharged from the upper chamber through the lower chamber, pressure loss increases with respect to the exhaust pipe without the silencer, which may lead to deterioration of power generation efficiency.
(C) Japanese Patent Laid-Open No. 2006-200369 (no sound absorbing material is used)
Compared with the case of using a sound-absorbing material that does not contain water (in a dry state), the noise reduction effect is low at the same volume. In addition, if the flow velocity of the gas flowing through the exhaust pipe at high speed and high output is increased, noise due to airflow (aerodynamic noise) is generated inside the silencer, and the silencing performance is degraded.

JP 2004-156555 A JP 2002-206413 A JP 2006-200369 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a noise reduction structure for an exhaust sound of a fuel cell vehicle that can effectively improve the noise reduction performance while eliminating the disadvantages of the prior art in an environment where the exhaust gas contains water vapor. There is.

The present invention for achieving the above object is as follows.
(1) A silencing structure for reducing the exhaust noise of a fuel cell vehicle,
An extension chamber that extends above the lower end of the linear portion and on the outer peripheral side is provided in a part of the linear portion of the exhaust pipe passage that extends in a straight line in the exhaust gas flow direction, and the expansion chamber has a large number of through holes. Is divided into two regions, a resonance chamber on the inner peripheral side and a sound absorption chamber on the outer peripheral side,
The resonance chamber is provided with a partition member that partitions the internal space of the resonance chamber into a plurality, and forms a plurality of resonance type silencers having different resonance frequencies,
The sound absorbing chamber is filled with a sound absorbing material,
The opening part of the resonance silencer formed in the resonance chamber is located on the outer peripheral side than the diameter of the straight part of the exhaust pipe flow path,
The outer peripheral side end of the connection R portion between the exhaust pipe downstream side portion downstream of the expansion chamber in the exhaust gas flow direction and the expansion chamber constituting wall constituting the expansion chamber is located on the outer peripheral side from the opening portion. In addition, it has a silencer structure for the exhaust noise of fuel cell vehicles.

According to the structure (1) of the structure for silencing exhaust gas from a fuel cell vehicle, the following effects can be obtained.
(I) The expansion chamber is provided above the lower end of the straight portion of the exhaust pipe passage and on the outer peripheral side, and is provided with a partition plate in which a large number of through holes are formed. The sound absorbing chamber is divided into two regions, and the sound absorbing chamber is filled with a sound absorbing material. Therefore, the moisture adhering to the sound absorbing material falls to the resonance chamber and the exhaust pipe flow path through the through holes, is discharged to the outside of the silencer together with the gas, and is discharged from the exhaust gas outlet to the outside of the exhaust pipe. Therefore, water (liquid) drips from the position where it can be visually observed, and the user can be prevented from feeling uneasy compared to the prior art (a).
(Ii) Since the expansion chamber is provided in a part of the exhaust gas flow direction of the straight portion extending linearly of the exhaust pipe flow path, the exhaust gas inlet to the expansion chamber and the exhaust gas outlet from the expansion chamber are opposed to each other Therefore, an increase in pressure loss can be suppressed as compared with the prior art (b).
(Iii) Since the sound absorbing chamber is filled with a sound absorbing material, the sound deadening effect is higher than that of the prior art (c).
(Iv) Since the opening part of the resonance silencer is located on the outer peripheral side of the diameter of the straight part of the exhaust pipe flow path, the degree of exhaust gas colliding with the partition member is small and the generation of airflow noise is suppressed. Is done.
(V) Since the outer peripheral side end of the connection R portion between the exhaust pipe downstream side portion and the expansion chamber constituting wall constituting the expansion chamber is located on the outer peripheral side from the opening portion of the resonance silencer, the expansion chamber Since a part of the gas flow that spreads on the outer peripheral side flows into the exhaust pipe flow path downstream from the expansion chamber, it is rectified at the connection R portion (R at the corner portion), so that the air flow is higher than in the conventional technique (c). Sound generation can be effectively suppressed.

It is a perspective view of the silence structure of the exhaust sound of the fuel cell vehicle of Example 1 of the present invention. It is the sectional view on the AA line of FIG. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is a perspective view of the silence structure of the exhaust sound of the fuel cell vehicle of Example 2 of this invention. It is CC sectional view taken on the line of FIG. It is the DD sectional view taken on the line of FIG.

In the following, an exhaust sound silencing structure (hereinafter also simply referred to as a silencing structure) of a fuel cell vehicle according to an embodiment of the present invention will be described with reference to FIGS. In the figure, UP indicates the upper side.
1 to 3 show a silencing structure of the first embodiment of the present invention, and FIGS. 4 to 6 show a silencing structure of the second embodiment of the present invention.
Portions common to all the embodiments of the present invention are denoted by the same reference numerals throughout the embodiments of the present invention.
First, parts common to all the embodiments of the present invention will be described.

  The silencer structure 1 of the embodiment of the present invention is provided to reduce the exhaust noise of a fuel cell vehicle. In the sound deadening structure 1 of the embodiment of the present invention, as shown in FIG. 1, an expansion chamber 7 is provided in a part of the exhaust gas flow direction F of the exhaust pipe flow path 5 which is an internal flow path of the exhaust pipe 3. . The silencing structure 1 uses the expansion chamber 7 as a space for silencing.

  The exhaust pipe flow path 5 has a straight portion 5a extending horizontally and linearly with the same cross-sectional area. The expansion chamber 7 is provided in a part of the straight portion 5a in the exhaust gas flow direction F. As shown in FIG. 3, the expansion chamber 7 extends to the upper side and the outer peripheral side including the lower end 5 a 1 from the lower end 5 a 1 of the linear portion 5 a. In the illustrated example, the case where the expansion chamber 7 extends to the upper side and the outer peripheral side including the center from the center in the vertical direction of the linear portion 5a is shown. The expansion chamber 7 is configured by an expansion chamber configuration wall 9. The expansion chamber 7 is an internal space of the expansion chamber constituting wall 9.

As shown in FIG. 1, the expansion chamber constituting wall 9 includes an outer peripheral arcuate wall 9a, a bottom wall 9b extending from the lower end of the arcuate wall 9a to the exhaust pipe 3, and an exhaust gas flow direction F of the arcuate wall 9a. A front wall 9c extending from the upstream end to the exhaust pipe 3 and a rear wall 9d extending from the downstream end of the arcuate wall 9a in the exhaust gas flow direction F to the exhaust pipe 3 are provided.
A connecting portion between the arc-shaped wall 9a and the bottom wall 9b, a connecting portion between the arc-shaped wall 9a and the front and rear walls 9c, 9d, a connecting portion between the bottom wall 9b and the front and rear walls 9c, 9d, the bottom wall 9b and the exhaust pipe 3 The connecting portions between the front and rear walls 9c, 9d and the exhaust pipe 3 are all R-shaped (round shape, curved shape) connecting R portions (R of corner portions) 10.

  As shown in FIG. 3, the expansion chamber 7 is divided into two regions, a resonance chamber 13 on the inner peripheral side and a sound absorption chamber 15 on the outer peripheral side, by a partition plate 11 having a large number of through holes 11 a. Yes. The partition plate 11 has substantially the same shape as a shape (similar shape) in which the arcuate wall 9a is made slightly smaller. The volume of the resonance chamber 13 may be larger or smaller than the volume of the sound absorption chamber 15, and may be the same as the volume of the sound absorption chamber 15. In the illustrated example, the volume of the resonance chamber 13 is larger than the volume of the sound absorption chamber 15.

As shown in FIG. 2, the resonance chamber 13 is provided with a partition member 17 that partitions the internal space of the resonance chamber 13 into a plurality (for example, five) in the exhaust gas flow direction F, and has a plurality of resonance frequencies having different resonance frequencies. A mold silencer 19 is formed. The partition member 17 has substantially the same shape as the similar shape of the front and rear walls 9c, 9d of the expansion chamber constituting wall 9. As shown in FIGS. 2 and 3, each opening portion 19 a (inner peripheral end of the partition member 17) of the plurality of resonance type silencers 19 is located on the outer peripheral side with respect to the diameter of the straight portion 5 a of the exhaust pipe flow path 5. positioned.
The sound absorbing chamber 15 is filled with a sound absorbing material 15a. The sound absorbing material is, for example, glass wool.

  As shown in FIG. 2, a connection R portion between the exhaust pipe downstream portion 3 a located downstream of the expansion chamber 7 in the exhaust gas flow direction F and the rear wall 9 d of the expansion chamber constituting wall 9 in the exhaust pipe 3. The outer peripheral side end 10a1 of 10 (10a) is located on the outer peripheral side from the opening 19a of the resonance silencer 19 (the inner peripheral end of the partition member 17).

Next, operations and effects of portions common to all the embodiments of the present invention will be described.
The expansion chamber 7 is provided to extend above the lower end 5a1 of the straight portion 5a of the exhaust pipe flow path 5 and to the outer peripheral side, and is provided with a resonance plate on the inner peripheral side by a partition plate 11 having a large number of through holes 11a. The chamber 13 and the outer sound absorption chamber 15 are divided into two regions. In addition, since the sound absorbing chamber 15 is filled with the sound absorbing material 15a, the water adhering to the sound absorbing material 15a falls into the resonance chamber 13 and the exhaust pipe flow path 5 through the through holes 11a, and together with the gas silencer (expanded) The chamber 7) is discharged to the outside and discharged from the exhaust gas outlet to the outside of the exhaust pipe 3. Therefore, water (liquid) drips from the position where it can be visually observed, and the user can be prevented from feeling uneasy compared to the prior art (a).

Since the expansion chamber 7 is provided in a part of the exhaust gas flow direction F of the linear portion 5a extending linearly of the exhaust pipe flow path 5, the exhaust gas inlet to the expansion chamber 7 and the exhaust gas outlet from the expansion chamber 7 are provided. And the increase in pressure loss can be suppressed as compared with the prior art (b).

Since the sound absorbing chamber 15 is filled with the sound absorbing material 15a, the sound deadening effect is higher than that of the prior art (c).

Since the opening 19a of the resonance silencer 19 is located on the outer peripheral side of the diameter of the straight portion 5a of the exhaust pipe flow path 5, the degree of exhaust gas colliding with the partition member 17 is small, and airflow noise is generated. Is suppressed.

The outer peripheral side end 10a1 of the connection R portion 10 (10a) between the exhaust pipe downstream side portion 3a and the expansion chamber constituting wall 9 constituting the expansion chamber 7 is located on the outer peripheral side from the opening portion 19a of the resonance silencer 19. Therefore, when a part of the gas flow spreading to the outer peripheral side in the expansion chamber 7 flows into the exhaust pipe flow path 5a downstream from the expansion chamber 7, it is rectified by the connection R portion 10 (10a). The generation of airflow noise can be effectively suppressed as compared with the technique (c).

Next, parts unique to each embodiment of the present invention will be described.
[Example 1] (FIGS. 1 to 3)
In the first embodiment of the present invention, it is as follows.
The inner peripheral end of the partition member 17 is a free end. The resonance silencer 19 is a side branch type.

The resonance chamber 13 has a tapered shape in which the diameter increases as the distance between the partition members 17 adjacent to each other changes, and the arcuate wall 9a of the expansion chamber constituting wall 9 moves downstream or upstream in the exhaust gas flow direction F. A plurality of resonant silencers 19 having different resonance frequencies are formed by at least one of the above. In the illustrated example, the resonance chamber 13 has a different resonance frequency only by making the arcuate wall 9a of the expansion chamber constituting wall 9 into a tapered shape having a diameter that increases toward the downstream side in the exhaust gas flow direction F. The case where the some resonance type silencer 19 which has this is formed is shown.

[Example 2] (FIGS. 4 to 6)
In the second embodiment of the present invention, the operation is as follows.
The inner peripheral ends of the plurality of partition members 17 are connected to each other by a second partition plate 21 that is similar to the partition plate 11 and has a large number of through holes 21a. The second partition plate 21 is divided into a region on the inner peripheral side and a region on the outer peripheral side with respect to the second partition plate 21.
The resonance silencer 19 is a porous type (Helmholtz type).

The resonance chamber 13 has a tapered shape in which the diameter increases as the distance between the partition members 17 adjacent to each other changes, and the arcuate wall 9a of the expansion chamber constituting wall 9 moves downstream or upstream in the exhaust gas flow direction F. A plurality of resonance types having different resonance frequencies by at least one of changing the diameter of the through hole 21a of the second partition member 21 and changing the plate thickness of the second partition member 21. A silencer 19 is formed.

DESCRIPTION OF SYMBOLS 1 Silencer structure 3 Exhaust pipe 3a Exhaust pipe downstream part 5 Exhaust pipe flow path 5a Straight line part 5a1 Lower end 7 of a straight part Expansion chamber 9 Expansion chamber structure wall 9a Arc-shaped wall 9b Bottom wall 9c Front wall 9d Rear wall 10, 10a Connection R portion 10a1 Outer peripheral end 11 Partition plate 11a Through hole 13 Resonant chamber 15 Sound absorbing chamber 15a Sound absorbing material 17 Partition member 19 Resonant silencer 19a Resonant silencer opening 21 Second partition plate 21a Through hole F Exhaust gas flow direction

Claims (1)

A silencing structure for reducing exhaust noise of a fuel cell vehicle,
An extension chamber that extends above the lower end of the linear portion and on the outer peripheral side is provided in a part of the linear portion of the exhaust pipe passage that extends in a straight line in the exhaust gas flow direction, and the expansion chamber has a large number of through holes. Is divided into two regions, a resonance chamber on the inner peripheral side and a sound absorption chamber on the outer peripheral side,
The resonance chamber is provided with a partition member that partitions the internal space of the resonance chamber into a plurality, and forms a plurality of resonance type silencers having different resonance frequencies,
The sound absorbing chamber is filled with a sound absorbing material,
The opening part of the resonance silencer formed in the resonance chamber is located on the outer peripheral side than the diameter of the straight part of the exhaust pipe flow path,
The outer peripheral side end of the connection R portion between the exhaust pipe downstream side portion downstream of the expansion chamber in the exhaust gas flow direction and the expansion chamber constituting wall constituting the expansion chamber is located on the outer peripheral side from the opening portion. In addition, it has a silencer structure for the exhaust noise of fuel cell vehicles.

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