U.S. patent application number 11/920432 was filed with the patent office on 2009-02-19 for noise eliminator for fuel cell.
Invention is credited to Takashi Kato, Toshiyuki Kondo, Kiyohiko Nagae, Hideaki Taniguchi, Kazunori Yanagihara.
Application Number | 20090045006 11/920432 |
Document ID | / |
Family ID | 37570581 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090045006 |
Kind Code |
A1 |
Kondo; Toshiyuki ; et
al. |
February 19, 2009 |
Noise Eliminator for Fuel Cell
Abstract
A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from the fuel cell, comprising an
inner pipe having a plurality of sound transmission holes formed in
its peripheral wall and allowing the exhaust gases to flow
therethrough and an outer shell disposed to surround the inner pipe
through a prescribed distance from the peripheral wall and
constituting a sound absorbing chamber with a sound absorbing
material filled in the clearance thereof from the inner pipe. The
sound transmission hole has an inner diameter of 3 mm or greater,
and a depth of 1.2 mm or less.
Inventors: |
Kondo; Toshiyuki;
(Aichi-ken, JP) ; Yanagihara; Kazunori;
(Aichi-ken, JP) ; Taniguchi; Hideaki; (Aichi-ken,
JP) ; Kato; Takashi; (Aichi-ken, JP) ; Nagae;
Kiyohiko; (Gifu-ken, JP) |
Correspondence
Address: |
KENYON & KENYON LLP
1500 K STREET N.W., SUITE 700
WASHINGTON
DC
20005
US
|
Family ID: |
37570581 |
Appl. No.: |
11/920432 |
Filed: |
June 21, 2006 |
PCT Filed: |
June 21, 2006 |
PCT NO: |
PCT/JP2006/312841 |
371 Date: |
November 15, 2007 |
Current U.S.
Class: |
181/252 |
Current CPC
Class: |
F01N 2510/00 20130101;
F01N 2240/32 20130101; F01N 1/10 20130101; F01N 1/04 20130101; F01N
1/085 20130101; F01N 1/083 20130101; H01M 8/04 20130101; F01N 1/086
20130101; H01M 8/0662 20130101; F01N 2470/20 20130101; F01N 2240/20
20130101; Y02E 60/50 20130101; F01N 2470/04 20130101 |
Class at
Publication: |
181/252 |
International
Class: |
F01N 1/10 20060101
F01N001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2005 |
JP |
2005-185371 |
Claims
1. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the sound transmission hole has an
inner diameter of 3 mm or greater and a depth of 1.2 mm or
less.
2. The noise eliminator for a fuel cell according to claim 1,
wherein the peripheral part of the sound transmission hole in the
inner pipe is formed with a wall thickness thinner than that of
other parts of the sound transmission hole.
3. The noise eliminator for a fuel cell according to claim 1,
wherein a rib reinforcing the inner pipe is formed between the
sound transmission holes.
4. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the sound transmission hole is formed
in the shape of an oval having a longitudinal axis along the axis
direction of the inner pipe.
5. The noise eliminator for a fuel cell according to claim 4,
wherein the direction of the longitudinal axis of the oval being
the sound transmission hole is substantially parallel to the axis
of the inner pipe.
6. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein there is formed a groove connecting the
adjoining sound transmission holes.
7. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the inner wall of the sound
transmission hole is formed in a saw-tooth shape.
8. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein a water repellant layer is formed in
the inner wall of the sound transmission hole.
9. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein a sound absorbing material is filled in
the inner side of the inner wall of the sound transmission
hole.
10. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the inner pipe is provided with a
stream drift member drifting an exhaust gas stream in such a manner
that the exhaust gas stream is prevented from directly impacting
the sound transmission hole, and wherein the stream drift member is
a louver in the inner-pipe inner wall, protruding in a manner
inclined from the upstream side of the sound transmission hole
towards a downstream direction.
11. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the inner pipe is provided with a
stream drift member drifting an exhaust gas stream in such a manner
that the exhaust gas stream is prevented from directly impacting
the sound transmission hole, and wherein the stream drift member is
a stream guide plate, provided at an upstream end of the inner
pipe, and guiding the exhaust gas stream to an area where no sound
transmission hole is formed.
12. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein a swirling flow generation member
generating a swirling flow along the inner-pipe inner wall is
provided in an upstream end of the inner pipe.
13. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein a vortex generation member generating a
vortex in the vicinity of the inner-pipe inner wall is provided in
the inner pipe.
14. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, the noise eliminator further comprising stream
guide means for causing a portion of the exhaust gas flowing into
the inner pipe to flow out from inside the inner pipe through the
upstream-side sound transmission holes to the sound absorbing
chamber, wherein the exhaust gas flowing out to the sound absorbing
chamber flows through the downstream-side sound transmission holes
back into the inner pipe.
15. The noise eliminator for a fuel cell according to claim 14,
wherein the stream guide means is a narrowed portion formed in the
path of the inner pipe.
16. The noise eliminator for a fuel cell according to claim 14,
wherein the stream guide means is a duct arranged in the inner-pipe
inner wall in a manner corresponding to the upstream-side sound
transmission hole.
17. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, the noise eliminator further comprising gas
injection means for injecting gas from outside the noise eliminator
directly to the sound absorbing chamber so that gas flows from the
sound absorbing chamber through the sound transmission holes into
the inner pipe.
18. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough; and an outer shell, arranged to
surround the inner pipe up to a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe, wherein the sound transmission hole and a
peripheral part thereof are formed in a manner projecting towards
the axis center of the inner pipe.
19. A noise eliminator for a fuel cell installed in an exhaust
system discharging exhaust gas from a fuel cell, the noise
eliminator comprising: an outer shell allowing exhaust gas to flow
therethrough; and an inner case having a plurality of through holes
formed in a peripheral wall thereof and constituting a sound
absorbing chamber with a sound absorbing material filled in the
interior thereof, wherein the inner case is arranged over the
entire stream path cross section of the outer shell such that all
the exhaust gas flowing through the outer shell flows through the
interior of the inner case.
20. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a structure providing
countermeasures against condensation of moisture in exhaust gas
with respect to a noise eliminator installed in an exhaust system
of fuel cell.
BACKGROUND ART
[0002] In fuel cells, a power generating reaction between fuel gas
supplied to the anode electrode and oxidizing gas supplied to the
cathode electrode occurs in an electrolyte, in conjunction with
moisture is produced. The produced moisture is discharged as fuel
cell exhaust gas, along with unused fuel gas and oxidizing gas,
through an exhaust system connected to the fuel cell. In such an
exhaust system, the gas stream may produce a sound of a relatively
high frequency, on the order of 500 Hz to 2000 Hz. In order to
reduce the noise produced by the gas stream, the exhaust system of
a fuel cell vehicle or the like is typically equipped with a sound
absorption type noise eliminator whose interior is packed with a
sound absorbing material (noise elimination material) such as glass
wool.
[0003] One example of a noise eliminator of this type is that
having the cross-sectional structure illustrated in FIG. 31. This
noise eliminator 100 includes an inner pipe 102 through which the
exhaust gas from the fuel cell flows, and an outer shell 104
surrounding the inner pipe 102. A sound absorbing material 106 such
as glass wool is filled between the inner pipe 102 and outer shell
104. A plurality of sound transmission holes 108 are formed in the
peripheral wall of the inner pipe 102. The sound radiated from the
sound transmission holes 108 toward the sound absorbing material
106 is attenuated while subjected to repeated scattering and
interference in the sound absorbing material 106, and is
consequently absorbed by the sound absorbing material 106.
[0004] Meanwhile, fuel cell exhaust gases contain a large amount of
moisture produced by the reaction of hydrogen and oxygen. This
moisture may condense in the exhaust system upstream to form liquid
water which flows into the noise eliminator, or the moisture may
condense in the interior of the noise eliminator. As a result,
water may accumulate in the vertical lower part (hereinafter
referred to as the bottom part) of the noise eliminator. When this
happens, because the sound absorbing material filled in the bottom
part of the noise eliminator absorbs and holds the water ("contains
water"), a specified sound absorption performance cannot be
achieved, and, thus, noise elimination performance is impaired.
[0005] Means of addressing this problem have been proposed in the
conventional art, such as, for example, the noise eliminator 120
proposed in Japanese Patent Laid-Open Publication No. 2002-206413.
As illustrated in FIG. 32 of that publication, in the noise
eliminator 120, the interior of the noise eliminator 120 is
vertically partitioned into upper and lower parts by a partition
board 124 having a continuous hole 123, whereby a sound absorbing
chamber 126 and expansion chamber 128 are formed. An inner pipe 130
having sound transmission holes 136 is arranged inside the sound
absorbing chamber 126, and a sound absorbing material is filled to
surround the inner pipe 130. With this structure, even when the
sound absorbing material 126 in the vertical lower side of the
inner pipe 130 contains water, it is possible to cause the water to
drip through the continuous hole 123 of a partition board 124 into
the expansion chamber 128. The water falling into the expansion
chamber 128 is successively discharged through the sound
transmission holes 136 of a guiding pipe 134 to the outside of the
noise eliminator 120.
[0006] However, in the noise eliminator of Japanese Patent
Laid-Open Publication No. 2002-206413, the water flowing from the
exhaust system upstream into the noise eliminator or the water,
contained in exhaust gas, and condensing in the interior of the
noise eliminator can cause a water film to be produced in the inner
pipe or sound transmission holes. When a water film is produced in
the sound transmission holes, much of the sound energy in the inner
pipe or the guiding pipe is not discharged through the sound
transmission holes to the sound absorbing chamber and expansion
chamber, impairing the noise elimination performance of the noise
eliminator. Thus, there has been a need for a tangible approach for
suppressing formation of a water film in the sound transmission
holes.
DISCLOSURE OF THE INVENTION
[0007] The present invention provides a noise eliminator allowing
suppression of formation of a water film in sound transmission
holes. A noise eliminator for a fuel cell according to the present
invention includes an inner pipe having a plurality of sound
transmission holes formed in a peripheral wall thereof and allowing
exhaust gas to flow therethrough, and an outer shell, arranged to
surround the inner pipe through a prescribed distance from the
peripheral wall, and constituting a sound absorbing chamber with a
sound absorbing material filled in a space between the outer shell
and the inner pipe. The shape of the sound transmission holes is
configured so that no liquid film is formed in the holes. Also, the
shape of the sound transmission hole can be construed to have a
function of reducing liquid surface tension in the hole.
[0008] The noise eliminator for a fuel cell according to the
present invention has the following configurations.
[0009] (1) In one configuration, a noise eliminator for a fuel cell
according to the present invention is characterized by including an
inner pipe having a plurality of sound transmission holes formed in
a peripheral wall thereof and allowing exhaust gas to flow
therethrough, and an outer shell, arranged to surround the inner
pipe through a prescribed distance from the peripheral wall, and
constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein the sound transmission hole has an inner diameter of
3 mm or longer and a depth of 1.2 mm or shorter.
[0010] Here, the peripheral part of the sound transmission hole in
the inner pipe is preferably formed thinner in wall thickness than
the other part thereof.
[0011] Also, a rib reinforcing the inner pipe is preferably formed
between the sound transmission holes.
[0012] (2) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein the sound transmission hole is formed in the shape of
an oval having a longitudinal axis along the axis direction of the
inner pipe.
[0013] (3) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein there is formed a groove connecting the adjoining
sound transmission holes.
[0014] (4) In still another configuration, a noise eliminator for a
fuel cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein the inner wall of the sound transmission hole is
formed with a saw-tooth shape.
[0015] (5) In yet another configuration, a noise eliminator for a
fuel cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein a water repellant layer is formed in the inner wall
of the sound transmission hole.
[0016] (6) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein a sound absorbing material is filled in the inner
side of the inner wall of the sound transmission hole.
[0017] (7) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein the inner pipe is provided with a drift member
drifting an exhaust gas stream so that the exhaust gas stream is
prevented from directly impacting the sound transmission hole.
[0018] Here, the drift member is preferably a louver protruding in
a manner inclined from an upstream end of the sound transmission
hole to a downstream direction in the inner-pipe inner wall.
[0019] Also, the drift member may be arranged in the inner wall of
an upstream portion of the inner pipe, being preferably a stream
guide plate which guides exhaust gas to an area where no sound
transmission hole is formed.
[0020] (8) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including a swirling stream generation member for generating a
swirling stream along the inner pipe inner wall, the member being
disposed upstream in the inner pipe.
[0021] (9) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein a vortex generation member generating a vortex in the
vicinity of the inner-pipe inner wall is arranged in the inner
pipe.
[0022] (10) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including stream guide means for causing a part of exhaust gas
flowing into the inner pipe to flow out from inside the inner pipe
through the upstream-side sound transmission holes to the sound
absorbing chamber, wherein the exhaust gas flowing out to the sound
absorbing chamber flows through the downstream-side sound
transmission holes back into the inner pipe.
[0023] Here, the stream guide means may be a narrowed portion
formed in the path of the inner pipe, or the stream guide means may
be a duct arranged in the inner-pipe inner wall in a manner
corresponding to the upstream-side sound transmission hole.
[0024] (11) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, the noise eliminator further including gas injection means
for injecting gas from outside the noise eliminator directly to the
sound absorbing chamber so that gas flows from the sound absorbing
chamber through the sound transmission holes into the inner
pipe.
[0025] (12) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an inner pipe having a plurality of sound transmission
holes formed in a peripheral wall thereof and allowing exhaust gas
to flow therethrough, and an outer shell, arranged to surround the
inner pipe through a prescribed distance from the peripheral wall,
and constituting a sound absorbing chamber with a sound absorbing
material filled in a space between the outer shell and the inner
pipe, wherein the sound transmission hole and a peripheral part
thereof are formed in a manner projecting toward the axis center of
the inner pipe.
[0026] (13) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including an outer shell allowing exhaust gas to flow therethrough,
and an inner case having a plurality of through holes formed in a
peripheral wall thereof and constituting a sound absorbing chamber
with a sound absorbing material filled in the interior thereof,
wherein the inner case is arranged over the entire stream path
cross section of the outer shell so that all the exhaust gas
flowing through the outer shell flows through the interior of the
inner case.
[0027] (14) In another configuration, a noise eliminator for a fuel
cell according to the present invention is characterized by
including a shell allowing exhaust gas to flow therethrough, and a
plate-shaped member partitioning the interior of the shell by a
face thereof orthogonal to the direction of exhaust gas stream and
having a plurality of through holes formed therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a vertical section of a noise eliminator according
to a first embodiment of the present invention;
[0029] FIG. 2 is an expanded sectional view of an inner-pipe
peripheral wall in the noise eliminator according to the first
embodiment of the present invention, being an expanded sectional
view of the portion A in FIG. 1;
[0030] FIG. 3 is an expanded sectional view of an inner-pipe
peripheral wall in a noise eliminator according to a variation of
the first embodiment of the present invention, being an expanded
sectional view of the portion A of FIG. 1;
[0031] FIG. 4 is a vertical section of a noise eliminator according
to another variation of the first embodiment of the present
invention;
[0032] FIG. 5 is a view of an inner pipe having a cross section
illustrated in FIG. 4, as seen from the direction indicated by the
arrow D;
[0033] FIG. 6 is a view illustrating a configuration of a sound
transmission hole in a noise eliminator according to a second
embodiment of the present invention;
[0034] FIG. 7 is a view illustrating a configuration of a sound
transmission hole in a noise eliminator according to a variation of
the second embodiment of the present invention;
[0035] FIG. 8 is a view illustrating a configuration of a sound
transmission hole in a noise eliminator according to another
variation of the second embodiment of the present invention;
[0036] FIG. 9 is an expanded sectional view of an inner-pipe
peripheral wall in a noise eliminator according to a third
embodiment of the present invention, being an expanded sectional
view of the portion A in FIG. 1;
[0037] FIG. 10 is an expanded sectional view of an inner-pipe
peripheral wall in a noise eliminator according to a fourth
embodiment of the present invention, being an expanded sectional
view of the portion A in FIG. 1;
[0038] FIG. 11 is a vertical section of an inner pipe in a noise
eliminator according to a fifth embodiment of the present
invention;
[0039] FIG. 12 is an expanded sectional view of the inner-pipe
peripheral wall portion I in FIG. 11;
[0040] FIG. 13 is a view of the inner pipe having a cross section
illustrated in FIG. 11, as seen from the direction indicated by the
arrow D;
[0041] FIG. 14 is a vertical section of an inner pipe in a noise
eliminator according to a variation of the fifth embodiment of the
present invention;
[0042] FIG. 15 is a view schematically illustrating a vertical
cross section of a noise eliminator according to a sixth embodiment
of the present invention;
[0043] FIG. 16 is a view schematically illustrating a vertical
cross section of a noise eliminator according to a seventh
embodiment of the present invention;
[0044] FIG. 17 is a view illustrating an exemplary vortex
generation member arranged in the noise eliminator according to the
seventh embodiment of the present invention;
[0045] FIG. 18 is a vertical section of an inner pipe in a noise
eliminator according to a variation of the seventh embodiment of
the present invention;
[0046] FIG. 19 is a view of the inner pipe having a cross section
illustrated in FIG. 18, as seen from the direction indicated by the
arrow D;
[0047] FIG. 20 is a view schematically illustrating a vertical
cross section of a noise eliminator according to an eighth
embodiment of the present invention;
[0048] FIG. 21 is a vertical section of an inner pipe in a noise
eliminator according to a variation of the eighth embodiment of the
present invention;
[0049] FIG. 22 is a view of the inner pipe having a cross section
illustrated in FIG. 21, as seen from the direction indicated by the
arrow D;
[0050] FIG. 23 is a view schematically illustrating a noise
eliminator according to a ninth embodiment of the present
invention, and a peripheral device;
[0051] FIG. 24 is a vertical section of a noise eliminator
according to a tenth embodiment of the present invention;
[0052] FIG. 25 is a view of the inner pipe having a cross section
illustrated in FIG. 24, as seen from the direction indicated by the
arrow D;
[0053] FIG. 26 is a view schematically illustrating a vertical
cross section of a noise eliminator according to an eleventh
embodiment of the present invention;
[0054] FIG. 27 is a perspective view of an inner case in a noise
eliminator according to the eleventh embodiment of the present
invention;
[0055] FIG. 28 is a vertical section of a noise eliminator
according to a twelfth embodiment of the present invention;
[0056] FIG. 29 is a view of a plate-shaped member in the noise
eliminator according to the twelfth embodiment of the present
invention, as seen from a direction indicated by the arrow D of
FIG. 28;
[0057] FIG. 30 is a view illustrating an exemplary schematic
configuration of a fuel cell system;
[0058] FIG. 31 is a transverse sectional view of a sound absorption
type noise eliminator; and
[0059] FIG. 32 is a vertical section of a noise eliminator
described in Japanese Patent Laid-Open Publication No.
2002-206413.
BEST MODE FOR CARRYING OUT THE INVENTION
[0060] Embodiments of the present invention will be described in
detail below with reference to the drawings.
(1) First Embodiment
[0061] An exhaust system of a fuel cell system in which a noise
eliminator 10 of the present embodiment is used will be
schematically described with reference to FIG. 30. The fuel cell
system 80 includes a fuel cell 82, a hydrogen tank 84 supplying
hydrogen gas to the fuel cell 82, a blower 86 supplying oxidizing
gas to the fuel cell 82, and an exhaust system 88 (indicated by the
two-dot chain line in FIG. 30) discharging exhaust gas from the
fuel cell 82.
[0062] The hydrogen tank 84 is joined through a fuel gas supplying
path 85 to the fuel cell 82, and hydrogen gas (fuel gas) stored in
the hydrogen tank 84 is supplied, after being subjected to flow
rate adjustment by a regulator 90, through a control valve 92 to
the fuel cell 82. The blower 86 is connected through an oxidizing
gas supplying path 87 to the fuel cell 82, whereby oxidizing gas
(air) is supplied to the fuel cell 82. In the fuel cell 82, the
supplied hydrogen gas and air react to produce electric energy and
at the same time produce moisture.
[0063] Air unused in the reaction and oxidizing gas containing
moisture (water vapor) produced in the fuel cell are discharged
from the fuel cell 82 through a given exhaust system. The noise
eliminator 10 is disposed at the tail end of this exhaust system;
the exhaust gas containing moisture, and water being the result of
moisture contained in exhaust gas condensing in the interior of the
preceding exhaust system relative to the noise eliminator 10 flow
from the upstream end of the exhaust system upstream (the end
indicated by the arrow D of FIG. 1) into the noise eliminator
10.
[0064] The noise eliminator according to the present embodiment is
arranged in the exhaust system of the above described fuel cell
system. More specifically, the noise eliminator is installed as an
exhaust sound noise elimination device (muffler) for a fuel cell
vehicle in the underbody (not illustrated) towards the rear of the
vehicle hung by a bracket or the like.
[0065] The noise eliminator 10 according to the present embodiment
will be described with reference to FIGS. 1 to 4. FIG. 1
illustrates a vertical section configuration of the noise
eliminator; FIG. 2 illustrates an expanded sectional view of the
section of the inner-pipe peripheral wall A in FIG. 1; FIG. 3
illustrates an expanded sectional view of another example
inner-pipe peripheral wall; FIG. 4 illustrates a vertical section
configuration of a another example noise eliminator; and FIG. 5
illustrates a view of an inner pipe having a cross section
illustrated in FIG. 4, as seen from the direction indicated by the
arrow D.
[0066] The noise eliminator 10 includes, as illustrated in FIG. 1,
an outer shell 12 constituting the outer covering of the noise
eliminator and an inner pipe 14, arranged within the outer shell
12, and allowing exhaust gas to flow therethrough. A sound
absorbing material 16 is filled between the inner pipe 14 and outer
shell 12, to thereby form a sound absorbing chamber 17. As
indicated by the arrow D, the exhaust gas flowing from the exhaust
system upstream side into the noise eliminator passes through the
inner pipe 14 and is discharged to the outside of the noise
eliminator 10. The sound transmitted along with the exhaust gas
from the exhaust system upstream side into the inner pipe 14 is
radiated from sound transmission holes 18 arranged in a peripheral
wall 13 of the inner pipe 14 toward the sound absorbing material
16, and absorbed by the sound absorbing material 16. In this way,
the noise eliminator 10 achieves a given noise elimination
performance.
[0067] The inner pipe 14 is, as illustrated in FIG. 2, constituted
of an outer pipe section 20 having a plurality of sound
transmission holes 18 formed in a peripheral wall 13 thereof, and
an inner pipe section 22, installed in the inner side of the
peripheral wall 13 of the outer pipe section 20, and reinforcing
the outer pipe section 20. The outer pipe section 20 is made of
synthetic resin, the wall thickness (indicated by the size B in
FIG. 2) thereof being 1.2 mm or smaller. In the outer pipe section
20, there are formed many sound transmission holes 18, the inner
diameter of the sound transmission hole 18 (indicated by the size C
in FIG. 2) being set to 3 mm or larger.
[0068] Meanwhile, the wall thickness of the inner pipe section 22
is formed larger than the outer pipe section 20. In the inner pipe
section 22, there are formed a plurality of through holes 23 in a
manner corresponding to that used to form the above described sound
transmission holes 18. The configuration of the through hole is
designed so as not to seal the sound transmission hole 18 formed in
the outer pipe section 20 when the inner pipe section 22 is
installed in the outer pipe section 20. When the inner pipe section
22 having a relatively large wall thickness is inserted and welded
to the outer pipe section 20, the thin-walled outer pipe section 20
is reinforced.
[0069] With the above arrangement, the inner pipe 14 can be made of
synthetic resin and have a desired stiffness, and sound
transmission holes 18 having an inner diameter of 3 mm or greater
and a depth of 1.2 mm or less can be formed in the peripheral wall
of the inner pipe 14. The word "depth" used herein refers to the
length of the sound transmission hole 18 in the direction along the
center axis of the sound transmission hole 18 indicated by the
dashed line E in FIG. 2, and the wall thickness of the part (the
outer pipe section 20 in the present embodiment) in which the sound
transmission holes are formed.
[0070] While the inner diameter of the sound transmission hole 18
is 3 mm or larger, the depth thereof is set to a sufficiently small
value of 1.2 mm or less. While there is formed a water film having
a size corresponding to the inner diameter of the sound
transmission hole 18, because the area of the inner wall of the
sound transmission hole 18 holding the water film is small, it is
not possible for the inner wall of the sound transmission hole 18
to retain the water film. Consequently, in the noise eliminator 10
of the present embodiment, even when water flowing in from the
exhaust system upstream side or water condensing in the interior of
the noise eliminator attaches to the sound transmission holes,
formation of a water film in the sound transmission holes can be
suppressed.
[0071] In the noise eliminator 10 according to the present
embodiment, in order to implement the inner pipe of synthetic resin
having the sound transmission holes 18 of an inner diameter of 3 mm
or larger and a depth of 1.2 mm or smaller, the inner pipe section
22 reinforcing the outer pipe section 20 was inserted to the
interior of the thin-walled outer pipe section 20 in which the
sound transmission holes 18 are formed, but the structure of the
inner pipe is not limited thereto. The inner pipe can also be
implemented by various embodiments described below.
[0072] For example, as with the variation illustrated in FIG. 3, it
is also preferable that the wall of the peripheral part 24 of the
sound transmission hole 18 in the inner pipe 14b is formed smaller
than the other part 25. Here, the peripheral part 24 is a part
adjoining to the inner wall of the sound transmission hole 18 in
which the thickness closer to the inner wall of the sound
transmission hole 18 is less than elsewhere. In the inner wall of
the sound transmission hole 18, the wall thickness (indicated by
the size B) is 1.2 mm or less. The peripheral part 24 can be formed
by cutting or injection molding.
[0073] Meanwhile, "the other part" (indicated by reference numeral
25 in FIG. 3) which is at a longer distance from the sound
transmission hole 18 than the peripheral part 24, has a
sufficiently larger wall thickness than the part in which the sound
transmission hole 18 is formed.
[0074] In this way, when the peripheral part 24 of the sound
transmission hole 18 is formed thinner than the other part 25, it
is possible to provide in the inner pipe of synthetic resin a sound
transmission hole which ensures the stiffness of the inner pipe and
which has the dimensions described above which suppress formation
of a water film.
[0075] Also, as with the variation illustrated in FIGS. 4 and 5, it
is also preferable that a rib 28 reinforcing the inner pipe 14c is
formed between the sound transmission holes 18. In the inner pipe
14c, there is formed a rib 28 protruding from the inner wall 15
toward the axis center (indicated by F in FIG. 4) of the inner pipe
14c. This rib 28 is formed integrally with the inner pipe 14c; in
the inner wall of the inner pipe 14c are formed an axis-direction
rib 28a extending in a direction along the axis center of the inner
pipe 14c and a circular shaped rib 28b extending in a circular
shape in a direction orthogonal to the axis center of the inner
pipe 14c. These ribs 28 are formed between the sound transmission
holes 18 so as to avoid interfering with the sound transmission
holes formed in the inner pipe 14c.
[0076] Meanwhile, except the part in which the rib 28 is formed,
the inner pipe 14c is formed thinner to have a wall thickness of
1.2 mm or less; the sound transmission hole 18 is formed in this
part.
[0077] In this way, when the rib 28 is formed in the inner wall 15
of the thin-walled inner pipe, it is possible to provide in the
inner pipe 14c of synthetic resin the sound transmission hole 18 of
dimensions which suppress formation of a water film, while ensuring
the stiffness of the inner pipe 14.
(2) Second Embodiment
[0078] A noise eliminator 10b according to the present embodiment
will be described with reference to FIG. 6. FIG. 6 illustrates a
configuration of a sound transmission hole in the noise eliminator
illustrated in FIG. 1. FIG. 7 and illustrate alternative
configurations of a sound transmission hole according to the
present invention. In the noise eliminator 10b of the present
embodiment, the configuration of the sound transmission hole formed
in the inner pipe is differs from the noise eliminator 10 according
to the first embodiment, and will be described in detail. The same
reference numerals are applied to parts corresponding to the noise
eliminator 10 of the first embodiment, and explanation of these
parts will not be repeated.
[0079] According to the present embodiment, the sound transmission
hole 18b is oval-shaped as indicated by the solid line in FIG. 6.
This oval shape is an envelope configuration of a group of circles
produced by sliding a circle indicated by the two-dot chain line in
FIG. 6 in a given direction (indicated by the arrow G). That is,
the configuration of the sound transmission hole 18b is an oval
shape having its longitudinal axis in a direction indicated by the
arrow G. The distance from the center of the sound transmission
hole 18b indicated by the point E to the inner wall 19b in the
longitudinal axis direction (longitudinal direction of the sound
transmission hole 18) indicated by the arrow G is set longer than
the circle indicated by the two-dot chain line in FIG. 6.
[0080] When the configuration of the sound transmission hole 18b is
set in this manner, the sound transmission hole inner wall 19b
cannot retain a water film in the longitudinal axis direction of
the sound transmission hole 18b. Even if a water film forms in this
sound transmission hole 18b, the film is easily broken in the
longitudinal axis direction indicated by the arrow G. Consequently,
in the noise eliminator 10b of the present embodiment, even when
water flowing in from the exhaust system upstream or water
condensing in the interior of the noise eliminator attaches to the
sound transmission hole, formation of a water film in the sound
transmission hole can be suppressed.
[0081] Also, in the sound transmission hole 18b, the longitudinal
axis of the oval shape is set parallel to the axis center F of the
inner pipe 14. More specifically, the sound transmission hole 18b
is set so that the stream direction of exhaust gas passing through
the interior of the inner pipe 14 corresponds with the direction in
which the longitudinal axis of the sound transmission hole 18b is
set.
[0082] Accordingly, even if a water film forms in the sound
transmission hole 18b, the water film is unevenly distributed and
deformed in the longitudinal axis direction by the exhaust gas
stream passing through the inner pipe 14. Because thin portions of
the water film are thus formed, the film tension is easily broken.
Consequently, in the noise eliminator 10b of the present
embodiment, a water film can be suppressed from forming in the
sound transmission hole.
[0083] In the noise eliminator 10b of the present embodiment, in
order to suppress a water film from forming in the sound
transmission hole, the sound transmission hole was formed to have
an oval shape having its longitudinal axis along the axis direction
of the inner pipe 14; but the configuration of the sound
transmission hole is not limited thereto.
[0084] For example, as with the variation illustrated in FIG. 7, it
is also preferable that the inner wall 19c of the sound
transmission hole 18c is formed with a saw tooth shape. The
expression "saw tooth shape" used herein refers to a configuration
different from the circular-shaped sound transmission hole, in
which substantially triangle-shaped slits having the apex at a part
31 are successively formed. More specifically, in the sound
transmission hole inner wall 19c are alternately arranged a part 30
closer to the center axis of the sound transmission hole 18c
indicated by the point E and a part 31 at a longer distance from
the center axis.
[0085] When the configuration of the sound transmission hole 18c is
set in this manner, it is not possible for the sound transmission
hole inner wall 19c to retain a water film in the part 31 at a
longer distance from the center E of the sound transmission hole
18c. Thus, even if a water film forms in the sound transmission
hole 18c, the surface tension of the film is easily broken at the
part 31 farther from the center E, thus enabling suppression of
water film formation in the sound transmission hole.
[0086] Also, as with the variation illustrated in FIG. 8, it is
also preferable that there is formed a groove 32 connecting
adjoining sound transmission holes 18d and 18e. Between the
circular-shaped sound transmission holes 18d and 18e is arranged
the linear groove 32 connecting these holes through the shortest
distance. This groove 32 constitutes a communicating path which
causes the sound transmission holes 18d and 18e to communicate with
each other.
[0087] When such a groove 32 is provided, even if a water film
forms in these sound transmission holes 18, the water constituting
a water film in the one sound transmission hole 18 is pushed
through the groove 32 to the other sound transmission hole 18 by
effect of exhaust gas stream passing through the interior of the
inner pipe 14 or of acceleration acting on the noise eliminator
10b. For example, the water constituting a water film formed in the
sound transmission hole 18d can pass, as indicated by the arrow H,
through the groove 32 to the sound transmission hole 18e.
Accordingly, in the one sound transmission hole 18d, the amount of
water constituting a water film decreases and thus the water film
tension becomes easily breakable.
[0088] Consequently, according to the noise eliminator of the
present embodiment, each time the sound transmission holes 18d and
18e is subjected to effects of exhaust gas stream inside the inner
pipe 14 or of acceleration, the number of sound transmission holes
in which a water film forms can be reduced, thus allowing
suppression of water film formation in the sound transmission
holes.
(3) Third Embodiment
[0089] A noise eliminator 10c according to the present embodiment
will be described with reference to FIG. 9. FIG. 9 illustrates an
expanded sectional view of the portion of the inner-pipe peripheral
wall A in FIG. 1. The noise eliminator 10c of the present
embodiment differs from the noise eliminator 10 of the first
embodiment in that a water repellent finish is applied to sound
transmission holes, and will be described in detail below. The same
reference numerals are applied to parts corresponding to the noise
eliminator 10 of the first embodiment, and an explanation thereof
will not be repeated.
[0090] According to the present embodiment, in the inner wall 19d
of a sound transmission hole 18, as illustrated in FIG. 9, there is
formed a water repellent layer 34. In this water repellent layer
34, a water repellent film of fluorine resin or the like is formed
in the inner wall 19d. In this case, the water repellent layer 34
may be formed not only in the sound transmission hole inner wall
19d but also in the entire inner pipe 14d. When a water repellent
finish is applied to the entire inner pipe 14d, the water repellent
finish application process can be simplified.
[0091] When the above described water repellent finish is applied
and the water repellent layer 34 is formed at least in the inner
wall 19d of the sound transmission hole 18, the inner wall 19d of
the sound transmission hole 18 cannot hold a water film.
Accordingly, in the noise eliminator 10c of the present embodiment,
even when water flowing in from the exhaust system upstream or
water condensing in the interior of the noise eliminator attaches
to the sound transmission hole, formation of a water film in the
sound transmission hole can be suppressed.
(4) Fourth Embodiment
[0092] A noise eliminator 10d according to the present embodiment
will be described with reference to FIG. 10. FIG. 10 illustrates an
expanded sectional view of the portion of the inner-pipe peripheral
wall 13 A in FIG. 1. The noise eliminator 10d of the present
embodiment differs from the noise eliminator 10 of the first
embodiment in that a sound absorbing material is filled in the
inner side of the inner wall of a sound transmission hole, and will
be described in detail below. The same reference numerals are
applied to parts corresponding to the noise eliminator 10 of the
first embodiment, and their explanation will not be repeated.
[0093] According to the present embodiment, a sound absorbing
material 16b is, as illustrated in FIG. 10, filled in the inner
wall 19d of a sound transmission hole 18. In the sound absorbing
material 16b, a short projection 36 is integrally formed by press
molding or the like. When the sound absorbing material 16b is
placed around the inner pipe 14e, the projection 36 of the sound
absorbing material 16b fits into the inner side of the inner wall
19 of the sound transmission hole 18 formed in the inner pipe 14e.
The configuration of the projection 36 is set according to the
configuration of the sound transmission hole 18. In this manner,
the sound absorbing material 16b is filled in the inner side of the
sound transmission hole 18.
[0094] According to this configuration, in the noise eliminator 10d
of the present embodiment, when water flowing in from the exhaust
system upstream, or water condensing in the interior of the noise
eliminator 10d attaches to the sound transmission hole 18, it also
naturally attaches to the projection 36 of the sound absorbing
material 16b, disposed in the inner side of the sound transmission
hole 18. The water attaching to the projection 36 disperses to
parts other than the projection 36 of the sound absorbing material
16b by the capillary phenomenon. Consequently, the projection 36 of
the sound absorbing material 16b does not continue to be all
wet.
[0095] Accordingly, even if a water film forms in the sound
transmission hole 18, the water constituting this water film is
made to disperse to another part of the sound absorbing material
16b by the projection 36 of the sound absorbing material 16b and
thus the tension of the film forming in the sound transmission hole
18 is easily broken. Consequently, in the noise eliminator 10 of
the present embodiment, even when water flowing in from the exhaust
system upstream or water condensing in the interior of the noise
eliminator attaches to the sound transmission hole, formation of a
water film in the sound transmission hole can be suppressed.
(5) Fifth Embodiment
[0096] A noise eliminator 10e according to the present embodiment
will be described with reference to FIGS. 11, 12 and 13. FIG. 11
illustrates a cross section of an inner pipe; FIG. 12 illustrates
an expanded sectional view of the section of the inner-pipe
peripheral wall I in FIG. 11; FIG. 13 illustrates a view of the
inner pipe having a cross section illustrated in FIG. 11, as seen
from the direction indicated by the arrow D; and FIG. 14
illustrates a cross section of an inner pipe in a noise eliminator
according to a variation. The noise eliminator 10d of the present
embodiment differs from the noise eliminator 10 of the first
embodiment in that the inner pipe is provided with a drift member
drifting the exhaust gas stream, as will be described in detail
below. The same reference numerals are applied to parts
corresponding to the noise eliminator 10 of the first embodiment,
and their explanation will not be repeated.
[0097] The inner pipe 14 is provided with a drift member drifting
the exhaust gas stream so that the exhaust gas stream does not
impact directly against the sound transmission hole 18. The drift
member is arranged inside the inner pipe 14; because the exhaust
gas stream containing moisture does not directly impact against the
sound transmission hole 18, fixing of the moisture contained in the
exhaust gas stream to the sound transmission hole 18 is suppressed
to a great extent. In the noise eliminator 10 of the present
embodiment, the drift member is arranged inside the inner pipe 14
to prevent the exhaust gas stream from impacting against the sound
transmission hole 18; thus, formation of a water film in the sound
transmission hole 18 can be suppressed.
[0098] According to the present embodiment, a louver 38 as
illustrated in FIG. 11, is provided as the drift member in a
protruding manner upstream of the sound transmission hole 18 in the
inner-pipe inner wall 15. More specifically, the louver 38
protrudes as illustrated in FIG. 12, from the upstream end of the
sound transmission hole 18 toward the inner pipe axis center F and
at the same time in a manner inclined toward a downstream direction
(direction indicated by the arrow D).
[0099] As indicated by the arrow J in FIG. 12, the exhaust gas
stream flowing along the inner-pipe inner wall 15 is polarized
upstream of the sound transmission hole 18 toward the side having
the inner pipe axis center F by the louver 38. Consequently, the
exhaust gas stream flowing inside the inner pipe 14f does not
directly impact against the sound transmission hole 18 in the
downstream of the louver 38, and thus little of the moisture
contained in the exhaust gas attaches to the walls of the sound
transmission hole 18.
[0100] In addition, the louver 38 is as illustrated in FIG. 13,
preferably arranged in a circular shape to cover the entire
circumference of the inner-pipe inner wall 15. The louver 38 having
such a circular configuration not only polarizes the exhaust gas
stream inside the inner pipe 14f, but also functions as a "rib"
reinforcing the inner pipe 14f. When the inner pipe 14f is
reinforced by the louver 38, the stiffness of the inner pipe 14f
can be improved. As a result, the thickness of the peripheral wall
13 of the inner pipe 14f can be set thinner.
[0101] In the noise eliminator 10e of the present embodiment, as
the drift member drifting the exhaust gas stream to prevent the
exhaust gas stream from impacting directly against the sound
transmission hole 18, the louver 38 protruding from the upstream
end of the sound transmission hole 18 is provided, but the drift
member is not limited to this configuration.
[0102] For example, as with a variation illustrated in FIG. 14, it
is also preferable to provide within the inner pipe 14g a stream
guide plate 40 guiding the exhaust gas stream to an area 39 in
which no sound transmission hole 18 is formed. The stream guide
plate 40 may be a plate-shaped member arranged in the inner wall 15
of an upstream side end 41 of the inner pipe 14g, the plate being
disposed in a manner inclined relative to the stream direction
(indicated by the arrow D) of exhaust gas flowing into the inner
pipe 14g. Then, the exhaust gas stream flowing into the upstream
side end 41 of the inner pipe 14g is as indicated by the arrow K in
FIG. 14, polarized by the stream guide plate 40 and guided to the
area 39 (area surrounded by the dashed line in FIG. 14) where no
sound transmission hole 18 is formed.
[0103] The "area 39 where no sound transmission hole 18 is formed"
refers to an area, downstream of the upstream end 41 of the inner
pipe 14g, and excluding the area 43 (indicated by the dotted line
in FIG. 14) where the sound transmission hole 18 is formed. The
stream guide plate 40 polarizes the exhaust gas stream flowing into
the inner pipe 14g so that the exhaust gas stream avoids this "area
43 where the sound transmission hole 18 is formed".
[0104] In this way, the exhaust gas stream does not directly impact
the "area 43 in which the sound transmission hole 18 is formed".
Consequently, very little of the moisture contained in the exhaust
gas attaches to the sound transmission hole 18.
[0105] As described above, in the noise eliminator 10e of the
present embodiment, the louver 38 protruding from the upstream side
of the sound transmission hole 18 is arranged inside the inner pipe
14g, or the stream guide plate 40 is arranged in the upstream side
end 41, and thus very little moisture attaches to the sound
transmission hole 18. Consequently, formation of a water film in
the sound transmission hole is suppressed.
(6) Sixth Embodiment
[0106] A noise eliminator 10f according to the present embodiment
will be described with reference to FIG. 15. FIG. 15 schematically
illustrates a cross section of the noise eliminator. The noise
eliminator 10f of the present embodiment differs from the noise
eliminator 10 of the first embodiment in that a swirling stream
(vortex) generation member is provided along the inner pipe inner
wall for generating a swirling stream, and will be described in
detail below. The same reference numerals are applied to parts
corresponding to the noise eliminator 10 of the first embodiment,
and their explanation will not be repeated.
[0107] According to the present embodiment, the swirling stream
generation member 44 is, as illustrated in FIG. 15, a plate-shaped
member having a twisted configuration and arranged in the upstream
end 41 inside the inner pipe 14h. This twisted plate-shaped member
generates a swirling stream swirling along the inner-pipe inner
wall 15. As indicated by the arrow b, the exhaust gas stream
flowing into the upstream end 41 of the inner pipe 14h swirls
around the inner pipe axis center F by the plate-shaped member.
This swirling exhaust gas stream (swirling stream) flows, as
indicated by the arrow L in FIG. 15, in a downstream direction
while swirling along the inner-pipe inner wall 15. Acting on the
exhaust gas swirling inside the inner pipe 14h is a centrifugal
force working toward the inner-pipe inner wall 15 around the axis
center of the inner pipe 14h.
[0108] Accordingly, in the noise eliminator 10f of the present
embodiment, even if a water film forms in the sound transmission
hole, the exhaust gas is pressed against the water film and thus
the film tension is easily broken. Consequently, in the noise
eliminator 10 of the present embodiment, formation of a water film
in the sound transmission hole can be suppressed.
[0109] Here, it is also preferable that the sound transmission hole
18f is, as illustrated in FIG. 15, formed to have a configuration
along the flow of the generated swirling stream. More specifically,
the sound transmission hole 18 is set so that the stream direction
(indicated by the arrow L) of the swirling stream agrees with the
longitudinal direction of the sound transmission hole 18f.
[0110] When the sound transmission hole 18f is configured in this
manner, even if a water film forms in the sound transmission hole
18f, the water film is polarized and deformed in the longitudinal
direction of the sound transmission hole 18f by the exhaust gas
stream (swirling stream) flowing along the inner-pipe inner wall
15, and, because the film includes thin patches, the film tension
is easily broken.
(7) Seventh Embodiment
[0111] A noise eliminator 10g according to the present embodiment
will be described with reference to FIGS. 16 to 19. FIG. 16
schematically illustrates a cross section of the noise eliminator;
FIG. 17 illustrates an exemplary vortex generation member arranged
in the noise eliminator; FIG. 18 illustrates a cross section of an
inner pipe in a noise eliminator according to a variation; and FIG.
19 illustrates a view of the inner pipe having a cross section
illustrated in FIG. 18, as seen from the direction indicated by the
arrow D. The noise eliminator 10g of the present embodiment differs
from the noise eliminator 10 of the first embodiment in being
provide with a vortex generation member generating a vortex along
the inner-pipe inner wall, and will be described in detail below.
The same reference numerals are applied to parts corresponding to
the noise eliminator 10 of the first embodiment, and their
explanation will not be repeated.
[0112] The inner pipe 14i is provided with a vortex generation
member generating a vortex in the vicinity of the inner wall 15 of
the inner pipe 14i. The vortex generation member produces a vortex
48 upstream of the sound transmission hole 18. The produced vortex
48 flows downstream along the inner wall of the inner pipe 14
towards the sound transmission hole 18. The turbulent flow of the
vortex 48 as it reaches the sound transmission hole 18 suppresses
formation of water films in the sound transmission hole 18, and,
upon impact, acts to break up any films that may have formed. In
the noise eliminator 10g of the present embodiment, because the
inner pipe 14i is provided with the vortex generation member to
produce a vortex in the vicinity of the inner-pipe inner wall 15,
formation of a water film in the sound transmission hole can be
suppressed.
[0113] According to the present embodiment, as the vortex
generation member, a Karman vortex generation member 46 is, as
illustrated in FIG. 16, arranged in the upstream end 41 of the
inner pipe 14i. The Karman vortex generation member 46 can be, as
illustrated in FIG. 17, composed of a plate-shaped member having
some thickness, for example. The member is disposed inside the
inner pipe 14i so that the axis center F of the inner pipe 14i
penetrates through the member.
[0114] The exhaust gas stream flowing into the inner pipe 14i from
the direction indicated by the arrow D is divided into two streams
(an upper stream and a lower stream indicated by the arrows M1 and
M2, respectively, in FIG. 16) by the Karman vortex generation
member 46. The two streams break away at a downstream end 46e of
the Karman vortex generation member 46 and alternately produce a
vortex 48. This Karman vortex 48 flows to the downstream side and
reaches the sound transmission hole 18. The turbulent flow of the
vortex 48 suppresses formation of water films in the sound
transmission hole 18, and acts to break up any films that do
form.
[0115] In the noise eliminator 10g of the present embodiment, the
Karman vortex generation member 48 produces a vortex in the
vicinity of the inner-pipe inner wall 15, but the vortex generation
member is not limited to this configuration.
[0116] For example, as with the variation illustrated in FIGS. 18
and 19, it is also preferable that there is arranged a protrusion
50 generating a vortex 51 in the vicinity of the inner-pipe inner
wall 15. A protrusion 50 may be, as illustrated in FIG. 18,
arranged for each sound transmission hole 18 in the upstream side
of the hole. Also, the protrusions 50 project, as illustrated in
FIG. 19, from the inner-pipe inner wall 15 toward the inner-pipe
axis center F. The protrusion 50 is configured so that the flow
along the inner wall 15 of the inner pipe 14j can be separated away
from the boundary layer as much as possible.
[0117] Of the exhaust gas stream flowing from a direction indicated
by the arrow D into the inner pipe 14j, the flow (indicated by the
arrow N in FIG. 18) along the inner-pipe inner wall 15 collides
with the protrusion 50 and separates from the inner wall 15, thus
generating a vortex 51 (turbulent flow). This vortex 51 reaches the
sound transmission hole 18 residing in the upstream side of the
protrusion 50. Accordingly, formation of a water film in the sound
transmission hole can be further suppressed.
(8) Eighth Embodiment
[0118] A noise eliminator 10h according to the present embodiment
will be described with reference to FIGS. 20 to 22. FIG. 20
schematically illustrates a vertical section of the noise
eliminator; FIG. 21 illustrates a vertical section of an inner pipe
in a noise eliminator according to a variation; and FIG. 22
illustrates a view of the inner pipe having a cross section
illustrated in FIG. 21, as seen from the direction indicated by the
arrow D. The noise eliminator 10 of the present embodiment differs
from the noise eliminator 10 of the first embodiment in that stream
guide means are provided for directing a portion of the exhaust gas
flowing into the inner pipe out from the upstream sound
transmission hole to the sound absorbing chamber. These stream
guide means will be described in detail below, but the same
reference numerals are applied to parts corresponding to the noise
eliminator 10 of the first embodiment, and their explanation will
not be repeated.
[0119] The stream guide means cause a portion of the exhaust gas
flowing inside the inner pipe 14 to flow out from inside the inner
pipe 14 through the sound transmission hole 18g in the upstream
side to the sound absorbing chamber 17. More specifically, in the
sound transmission hole 18g in the upstream side, the stream guide
means produce an exhaust gas stream flowing from inside the inner
pipe 14 to the sound absorbing chamber. 17. The sound absorbing
chamber 17 is a hermetically-closed space surrounded by the
inner-pipe outer wall and outer-shell inner wall, with the
exception of the sound transmission holes 18g and 18h, and the
exhaust gas flowing out from the sound transmission hole 18g in the
upstream side to the sound absorbing chamber 17 flows back from the
sound transmission hole 18h in the downstream side into the inner
pipe 14. In the sound transmission hole 18h in the downstream side,
there is produced an exhaust gas stream flowing from the sound
absorbing chamber 17 into the inner pipe 14.
[0120] When the stream guide means are arranged in the noise
eliminator 10h, an exhaust gas stream can be produced in such a
manner that a portion of the streams flows out from inside the
inner pipe 14 through the sound transmission hole 18g in the
upstream side to the sound absorbing chamber 17 and flows back
through the sound transmission hole 18h in the downstream side into
the inner pipe 14. Because the exhaust gas streams flows through
both the upstream and downstream sound transmission holes 18g and
18h, formation of water films in the sound transmission holes 18g
and 18h is suppressed, and any films that do form tend to be broken
by the exhaust gas stream flowing through the sound transmission
holes 18g and 18h. Accordingly, in the noise eliminator 10h of the
present embodiment, formation of a water film in the sound
transmission hole can be further suppressed.
[0121] According to the present embodiment, a narrowed section 52
as illustrated in FIG. 20 is formed in the inner pipe 14k as the
stream guide means. The narrowed section 52 is a portion in which
the cross sectional area (cross section orthogonal to the axis
center F of the inner pipe 14) of the stream path formed inside the
inner pipe 14k is smaller than elsewhere, and disposed in the path
of the inner pipe 14k. The sound transmission holes 18g and 18h are
formed upstream and downstream relative to this narrowed section
52, respectively.
[0122] When exhaust gas flows in from the direction indicated by
the arrow D, the pressure in the upstream side relative to the
narrowed section 52 in the inner pipe 14k increase. On the other
hand, downstream of the narrowed section 52 in the inner pipe 14k,
the pressure becomes lower than in upstream side relative to the
narrowed section 52. In this way, when the narrowed section 52 is
formed in the inner pipe 14k, a pressure differential between the
flow upstream and downstream of the narrowed section 52 is created,
causing a portion of the exhaust gas flowing upstream of the
narrowed section 52 in the inner pipe 14k to flow out from the
upstream-side sound transmission hole 18 to the sound absorbing
chamber 17. Further, the exhaust gas flowing out to the sound
absorbing chamber 17 flows, as indicated by the arrow P in FIG. 20,
in a downstream direction inside the sound absorbing chamber 17,
and then flows through the downstream sound transmission hole 18h
into the downstream side relative to the narrowed section 52 in the
inner pipe 14k.
[0123] In this way, in the noise eliminator 10h of the present
embodiment, because the narrowed section 52 is arranged in the
inner pipe 14k, exhaust gas streams flowing from inside the inner
pipe 14k through the sound transmission hole 18g in the upstream
side into the sound absorbing chamber 17, and flowing from the
sound absorbing chamber 17 through the sound transmission hole 18h
in the downstream side into the inner pipe 14k, are produced.
Accordingly, water films rarely form in the upstream and downstream
sound transmission holes 18g and 18h, and any films that do form
are easily broken by the exhaust gas stream flowing through the
sound transmission holes 18g and 18h.
[0124] In the noise eliminator 10h of the present embodiment, the
formation of the narrowed section 52 in the inner pipe 14k allows a
portion of the exhaust gas to flow out through the upstream sound
transmission hole 18g into the sound absorbing chamber 17, but the
stream guide means are not limited to this configuration.
[0125] For example, as with the variation illustrated in FIGS. 21
and 22, it is also preferable that there is arranged a duct 54
corresponding to the upstream sound transmission hole 18g. The duct
54 may be, as illustrated in FIG. 21, arranged in the inner wall 15
of the inner pipe 141 in a manner corresponding to each of the
upstream sound transmission holes 18. Also, the duct 54 may
protrude, as illustrated in FIG. 22, from the inner wall 15 of the
inner pipe 141 toward the axis center F of the inner pipe 141, and
have an opening facing the upstream side.
[0126] Of the exhaust gas streams flowing from a direction
indicated by the arrow D into the inner pipe 141, the stream
indicated by the arrow Q in FIG. 21, which flows along the
inner-pipe inner wall 15, flows from the opening of the duct 54
through the sound transmission hole 18 (in the upstream side) and
flows out into the sound absorbing chamber 17. Because the exhaust
gas flowing out into the sound absorbing chamber 17 raises the
pressure inside the sound absorbing chamber 17, the exhaust gas
flowing out into the sound absorbing chamber 17 flows back, as
indicated by the arrow R in FIG. 21, through the sound transmission
hole 18h in the downstream side into the inner pipe 141.
[0127] In this manner, providing for each upstream sound
transmission hole 18 a duct 54 having an upstream opening can
produce the exhaust gas streams flowing through the upstream and
downstream sound transmission holes 18i. As a result, formation of
a water film in the sound transmission hole can be further
suppressed.
(9) Ninth Embodiment
[0128] A noise eliminator 10i according to the present embodiment
will be described with reference to FIG. 23. FIG. 23 schematically
illustrates the noise eliminator and its peripheral device. The
noise eliminator 10i of the present embodiment is different from
the noise eliminator 10 of the first embodiment in being provided
with gas injection means for injecting gas into the sound absorbing
chamber, and will be described in detail below. The same reference
numerals are applied to parts corresponding to the noise eliminator
10 of the first embodiment, and their explanation will not be
repeated.
[0129] Separately from the exhaust gas stream flowing from the
upstream of the exhaust system into the inner pipe 14, the gas
injection means injects gas from the outside of the noise
eliminator 10i into the sound absorbing chamber 17. Because the
pressure of the injected gas is greater than the pressure inside
the inner pipe 14, when gas is injected into the sound absorbing
chamber 17, the gas inside the sound absorbing chamber 17 flows
through the sound transmission hole 18 into the inner pipe 14. In
this way, a stream flowing from inside the sound absorbing chamber
17 through the sound transmission hole 18 and into the inner pipe
14 can be produced.
[0130] Consequently, water film rarely form in the sound
transmission hole 18, and, even should such a film form, the stream
flowing through the sound transmission hole 18 acts to break up the
film. As a result, in the noise eliminator 10 according to the
present embodiment, formation of water films in the sound
transmission hole can be suppressed.
[0131] According to the present embodiment, a bypass stream path 60
which bypasses the fuel cell 82 and directly connects the oxidizing
gas supplying path 87 and the interior of the sound absorbing
chamber 17 as illustrated in FIG. 23 is provided as the gas
injection means. One end of the bypass stream path 60 is connected
to a gas outlet 57 arranged in the oxidizing gas supplying path 87
connecting a blower 86 and fuel cell body 82a; and the other end
thereof is connected to a gas inlet 58 arranged in the outer shell
12c. By connecting the bypass stream path 60 in this manner, the
oxidizing gas supplying path 87 is made to communicate with the
sound absorbing chamber 17 inside the outer shell 12.
[0132] Referring to FIG. 23, when the blower 86 supplies, as
indicated by the arrow S, oxidizing gas (air) through the oxidizing
gas supplying path 87 to the fuel cell body 82a, the oxidizing gas
is simultaneously supplied to the bypass stream path 60 (indicated
by the arrow T in FIG. 23). The oxidizing gas supplied to the
bypass stream path 60 flows, as indicated by the arrow U, through
the gas inlet 58 of the outer shell 12 into the sound absorbing
chamber 17. Meanwhile, the oxidizing gas supplied to the fuel cell
body 82a is discharged as oxidizing gas from the fuel cell body
82a, and subjected to flow rate adjustment by an adjustment valve
82b, and flows, as indicated by the arrow D, into the inner pipe 14
of the noise eliminator 10i.
[0133] Here, the pressure of oxidizing gas flowing in the bypass
stream path 60 (the pressure of oxidizing gas injected into the
sound absorbing chamber) is set higher than the pressure of exhaust
gas flowing in the inner pipe 14, so the oxidizing gas flowing
through the gas inlet 58 into the sound absorbing chamber 17 flows
from the sound absorbing chamber 17 through the sound transmission
hole 18 into the inner pipe 14.
[0134] In this way, the bypass stream path 60 directly connecting
the oxidizing gas supplying path 87 outside the noise eliminator 10
and the interior of the sound absorbing chamber 17 is provided in
the noise eliminator 10 of the present embodiment, such that a gas
stream flowing from the sound absorbing chamber 17 through the
sound transmission hole 18 into the inner pipe 14 can be formed.
Accordingly, formation of a water film in the sound transmission
hole can be further suppressed.
[0135] According to the present embodiment, oxidizing gas is
removed from the oxidizing gas supplying path to the bypass stream
path and injected into the sound absorbing chamber, but the
configuration is not limited thereto. For example, it is also
preferable that a gas outlet is arranged in an anode purge valve
intermittently discharging anode gas (hydrogen) and is connected to
the bypass stream path, whereby the anode gas is injected into the
sound absorbing chamber. With this configuration, gas is
intermittently supplied to the sound absorbing chamber and produces
a pressure wave when injected, and any water films forming in the
sound transmission hole 18 can be broken up by this pressure
wave.
[0136] It is also preferable that a valve (not illustrated) which
can be opened and closed instantaneously be provided in the bypass
stream path 60. The instantaneous opening or closing of this valve
produces a pressure wave in the oxidizing gas downstream of the
valve. When this pressure wave propagates through the sound
absorbing chamber 17 to the sound transmission hole 18.
[0137] It is also preferable that the adjustment valve 82b is
opened or closed instantaneously. Such instantaneous opening and
closing of the adjustment valve 82b produces a pressure wave as
indicated by the arrow D in the exhaust gas flowing into the inner
pipe 14. This pressure wave propagates from the inner pipe 14 to
the sound transmission hole 18, and again acts to break up any
water films forming in the sound transmission hole.
(10) Tenth Embodiment
[0138] A noise eliminator 10j according to the present embodiment
will be described with reference to FIGS. 24 and 25. FIG. 24
illustrates a vertical section of an inner pipe 14, while FIG. 25
illustrates a view of the inner pipe 14 having the cross section
illustrated in FIG. 24, as seen from the direction indicated by the
arrow D. The noise eliminator 10j of the present embodiment differs
from the noise eliminator 10 of the first embodiment in that the
sound transmission hole and the peripheral part thereof are formed
projecting towards the axis center F of the inner pipe, as will be
described in detail below. The same reference numerals are applied
to parts corresponding to the noise eliminator 10 of the first
embodiment, and their explanation will not be repeated.
[0139] According to the present embodiment, the sound transmission
hole 18i and its peripheral part 62 are, as illustrated in FIGS. 24
and 25, arranged to project from the inner wall 15 of the inner
pipe 14m toward the inner-pipe axis center F. The exhaust gas
(indicated by the arrow V) flowing along the inner wall 15 of the
inner pipe 14 is polarized toward the inner-pipe axis center F by
the peripheral part 62 of the sound transmission hole 18i, such
that a contracted flow area 64 (surrounded by the two-dot chain
line in FIG. 24) having a relatively rapid flow is produced between
the sound transmission hole 18i and the inner-pipe axis center F.
That is, the sound transmission hole 18i is exposed to the rapidly
flowing exhaust gas stream.
[0140] In this manner, in the noise eliminator 10i of the present
embodiment, even when a water film forms in the sound transmission
hole 18i, because the sound transmission hole 18i is exposed to a
relatively rapid flow, the water film is polarized towards a
downstream direction and deformed, such that portions of the film
are thinner and the film is, thus, easily broken or dispersed.
Consequently, formation of water films in the sound transmission
hole can be further suppressed.
(11) Eleventh Embodiment
[0141] A noise eliminator 10k according to the present embodiment
will be described with reference to FIGS. 26 and 27. FIG. 26
schematically illustrates a vertical cross section of the noise
eliminator, while FIG. 27 schematically illustrates a perspective
view of an inner case constituting the noise eliminator. The noise
eliminator 10k of the present embodiment differs from the noise
eliminator 10 of the first embodiment in including an outer shell
allowing exhaust gas to flow therethrough and an inner case, having
a plurality of through holes formed in a wall surface thereof, with
a sound absorbing material filled in the interior thereof, the
inner case being disposed over the entire cross section of the
outer-shell stream path, and will be described in detail below.
[0142] The inner case 66 is as illustrated in FIG. 27, a hard case
of a substantially rectangular shape having a plurality of through
holes 18j formed on the wall surface 68 thereof. In more detail, in
the wall surface 68 constituting the inner case 66, the sound
transmission hole 18j is formed in the upstream wall surface 68a
and the downstream wall surface 68b facing the wall surface 68a;
gas can flow therethrough from the upstream side wall surface 68a
to the downstream side wall surface 68b. The sound absorbing
material 16 is filled in the inner side of the inner case wall
surface 68, i.e., inside the inner case 66, which functions as a
sound absorbing chamber 17.
[0143] The inner case 66 described above is, as illustrated in FIG.
26, received and held in the inner side of the outer shell 12d. A
stream path 70 is formed in the inner side of the outer shell 12d,
and the inner case 66 is disposed so as to seal this stream path
70. In more detail, the wall surface 68 (the upstream side wall
surface 68a and the downstream side wall surface 68b) of the inner
case 66 having the sound transmission hole 18j is disposed over the
entire cross section of the stream path 70 inside the outer shell
12d.
[0144] When the noise eliminator 10k is configured in this manner,
all the exhaust gas flowing through the outer shell 12d flows, as
indicated by the arrow W, through the through hole 18j of the
inner-case wall surface 68 and the sound absorbing chamber 17
residing therein. Accordingly, in the noise eliminator 10k of the
present embodiment, formation of a water film in the through hole
18j can be suppressed.
[0145] It is preferable that the configuration of the inner case 66
and outer shell 12d is set so that the area of the wall surface 68
having the through hole 18j of the inner case 66 is maximized. When
the area of the wall surface 68 having the through hole 18j of the
inner case 66 is maximized and the number of the through holes 18j
is set accordingly, the pressure loss caused by exhaust gas flowing
through the inner case 66 can be reduced.
(12) Twelfth Embodiment
[0146] A noise eliminator 10m according to the present embodiment
will be described with reference to FIGS. 28 and 29. FIG. 28
illustrates a vertical section of the noise eliminator, while FIG.
29 illustrates a view of a plate-shaped member constituting the
noise eliminator, as seen from the direction indicated by the arrow
D. The noise eliminator 10m of the present embodiment is differs
from the noise eliminator 10 of the first embodiment in that it
includes a shell allowing exhaust gas to flow therethrough and a
plate-shaped member having a plurality of through holes formed
therein, the plate-shaped member partitioning the interior of the
shell by a face thereof orthogonal to the direction of exhaust gas
stream. The noise eliminator 10m will be described in detail
below.
[0147] The plate-shaped member 72 is a hard plate member having a
substantially circular shape as illustrated in FIG. 29. A plurality
of through holes 18k are formed in a wall surface 73 thereof.
Meanwhile, a stream path 75 having a substantially circular-shaped
cross section is, as illustrated in FIG. 28, formed inside the
shell 74. A plurality of the plate-shaped members 72 are arranged
inside the shell 74 so as to divide the stream path 75 inside the
shell 74 by a face thereof orthogonal to the stream direction
(direction indicated by the arrow D) of exhaust gas. That is, the
through hole 18k of the plate-shaped member 72 has the same through
direction as the direction of exhaust gas stream.
[0148] The exhaust gas flowing in from the direction indicated by
the arrow D flows, as indicated by the arrow D, through the through
hole 18k of the plate-shaped member 72. The exhaust gas stream
indicated by the arrow D is a turbulent flow produced upstream in
the exhaust system, and this turbulent flow is rectified when the
exhaust gas flows through the plurality of through holes 18k formed
in the plate-shaped member 72. In this way, the turbulent flow is
rectified each time it passes through the through holes 18k of each
plate-shaped member, whereby the sound propagating from the exhaust
system upstream to the interior of the shell 74 is silenced.
[0149] In the noise eliminator 10m of the present embodiment, the
flowing--in exhaust gas is reliably directed through the through
hole 18k of the plate-shaped member 72, and formation of water
films in the through hole 18k is thereby suppressed. As a result, a
desired noise elimination performance can be achieved without using
a sound absorbing material.
INDUSTRIAL APPLICABILITY
[0150] As described above, the noise eliminator for a fuel cell
according to the present invention is useful as a noise eliminator
in an exhaust system of a fuel cell.
* * * * *