U.S. patent application number 14/294554 was filed with the patent office on 2014-12-04 for holding sealing material, exhaust gas purifying apparatus, and method for manufacturing exhaust gas purifying apparatus.
This patent application is currently assigned to IBIDEN CO., LTD.. The applicant listed for this patent is IBIDEN CO., LTD.. Invention is credited to Hisashi ANDO, Yasutaka ITO, Reo UCHIMURA.
Application Number | 20140356242 14/294554 |
Document ID | / |
Family ID | 50828674 |
Filed Date | 2014-12-04 |
United States Patent
Application |
20140356242 |
Kind Code |
A1 |
UCHIMURA; Reo ; et
al. |
December 4, 2014 |
HOLDING SEALING MATERIAL, EXHAUST GAS PURIFYING APPARATUS, AND
METHOD FOR MANUFACTURING EXHAUST GAS PURIFYING APPARATUS
Abstract
A holding sealing material includes a laminate of a plurality of
mats and a film. The plurality of mats each include inorganic
fibers and have a rectangular shape in a plan view. The plurality
of mats are arranged in an order of longitudinal length from a
shortest longitudinal length to a longest longitudinal length. The
film is provided around a longest mat having the longest
longitudinal length among the plurality of mats. The longest mat
has a first main surface and a second main surface which is on a
side opposite to the first main surface and which is in contact
with a second longest mat. The film is adhered to the first main
surface and longitudinal side surfaces of the longest mat and is
adhered to the second main surface to allow the second main surface
to be partly exposed.
Inventors: |
UCHIMURA; Reo;
(Takahama-shi, JP) ; ANDO; Hisashi; (Takahama-shi,
JP) ; ITO; Yasutaka; (Takahama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IBIDEN CO., LTD. |
Ogaki-shi |
|
JP |
|
|
Assignee: |
IBIDEN CO., LTD.
Ogaki-shi
JP
|
Family ID: |
50828674 |
Appl. No.: |
14/294554 |
Filed: |
June 3, 2014 |
Current U.S.
Class: |
422/179 ;
277/607; 29/890.09 |
Current CPC
Class: |
B32B 2307/54 20130101;
F01N 3/2871 20130101; B01D 53/885 20130101; B32B 5/26 20130101;
B32B 7/12 20130101; Y10T 29/49826 20150115; Y10T 29/494 20150115;
B32B 1/08 20130101; B32B 27/12 20130101; B32B 27/32 20130101; F01N
2450/28 20130101; B32B 27/36 20130101; F01N 3/2853 20130101; F01N
3/2864 20130101; B32B 15/14 20130101 |
Class at
Publication: |
422/179 ;
29/890.09; 277/607 |
International
Class: |
B01D 53/88 20060101
B01D053/88; F01N 3/28 20060101 F01N003/28; F01N 13/00 20060101
F01N013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2013 |
JP |
2013-117145 |
Claims
1. A holding sealing material comprising: a laminate of a plurality
of mats each comprising inorganic fibers and having a rectangular
shape in a plan view, the plurality of mats arranged in an order of
longitudinal length from a shortest longitudinal length to a
longest longitudinal length; and a film provided around a longest
mat having the longest longitudinal length among the plurality of
mats, the longest mat having a first main surface and a second main
surface which is on a side opposite to the first main surface and
which is in contact with a second longest mat, the film being
adhered to the first main surface and longitudinal side surfaces of
the longest mat and being adhered to the second main surface to
allow the second main surface to be partly exposed.
2. The holding sealing material according to claim 1, wherein the
film adhered to surfaces of the longest mat is continuously wound
once around the longest mat in a direction perpendicular to a
longitudinal direction of the longest mat, the longest mat
comprises a winding start position and a winding end position on
the second main surface, and the winding start position and the
winding end position are spaced apart from each other.
3. The holding sealing material according to claim 1, wherein the
laminate of the plurality of mats comprises two mats.
4. The holding sealing material according to claim 3, wherein a
full length of the longest mat is from about 1.05 times to about
1.10 times a full length of the second longest mat in contact with
the longest mat.
5. The holding sealing material according to claim 3, wherein an
area where a first main surface of the second longest mat is in
direct contact with the second main surface of the longest mat is
from about 40% to about 90% of an entire area of the first main
surface of the second longest mat.
6. The holding sealing material according to claim 1, wherein the
film comprises at least one of polyester, high-density
polyethylene, and polypropylene.
7. The holding sealing material according to claim 1, wherein the
film has a thickness of from about 30 .mu.m to about 60 .mu.m.
8. The holding sealing material according to claim 1, wherein the
film is fixed on the laminate of the plurality of mats with an
adhesive or by thermocompression bonding.
9. The holding sealing material according to claim 1, wherein the
plurality of mats are bound by at least one band with no fixing
strength.
10. The holding sealing material according to claim 9, wherein the
band comprises paper or resin.
11. The holding sealing material according to claim 1, wherein the
plurality of mats are fixed to each other at at least one fixed
part.
12. The holding sealing material according to claim 11, wherein the
fixed part extends along a direction perpendicular to a
longitudinal direction of the laminate of the plurality of
mats.
13. The holding sealing material according to claim 12, wherein the
plurality of mats are fixed to each other at two fixed parts.
14. The holding sealing material according to claim 13, wherein a
distance between the two fixed parts is from about 1/20 to about
3/4 of a full length of a mat with a shortest full length.
15. The holding sealing material according to claim 11, wherein the
fixed part comprises thread, pressure-sensitive adhesive tape, or
an adhesive.
16. The holding sealing material according to claim 1, wherein a
thickness of each of the plurality of mats is from about 1.5 mm to
about 15 mm.
17. An exhaust gas purifying apparatus comprising: an exhaust gas
treating body; a metal casing accommodating the exhaust gas
treating body; a holding sealing material placed between the
exhaust gas treating body and the metal casing; and the holding
sealing material comprising: a laminate of a plurality of mats each
comprising inorganic fibers and having a rectangular shape in a
plan view, the plurality of mats arranged in an order of
longitudinal length from a shortest longitudinal length to a
longest longitudinal length, a longest mat having the longest
longitudinal length among the plurality of mats facing the metal
casing, a shortest mat having the shortest longitudinal length
among the plurality of mats facing the exhaust gas treating body;
and a film provided around the longest mat, the longest mat having
a first main surface and a second main surface which is on a side
opposite to the first main surface and which is in contact with a
second longest mat, the film being adhered to the first main
surface and longitudinal side surfaces of the longest mat and being
adhered to the second main surface to allow the second main surface
to be partly exposed.
18. The exhaust gas purifying apparatus according to claim 17,
wherein the film adhered to surfaces of the longest mat is
continuously wound once around the longest mat in a direction
perpendicular to a longitudinal direction of the longest mat, the
longest mat comprises a winding start position and a winding end
position on the second main surface, and the winding start position
and the winding end position are spaced apart from each other.
19. A method for manufacturing an exhaust gas purifying apparatus,
the method comprising: providing a plurality of mats each
comprising inorganic fibers and having a rectangular shape in a
plan view; arranging the plurality of mats in an order of
longitudinal length from a shortest longitudinal length to a
longest longitudinal length to form a laminate; adhering a film
around a longest mat having the longest longitudinal length among
the plurality of mats, the film being adhered to both main surfaces
and longitudinal side surfaces of the longest mat, part of one of
the main surfaces being exposed, said one of the main surfaces
being in contact with a second longest mat; winding the laminate of
the plurality of mats around an exhaust gas treating body so that a
shortest mat having the shortest longitudinal length faces the
exhaust gas treating body; and press-fitting the exhaust gas
treating body with the laminate of the plurality of mats into a
metal casing so that the longest mat faces the metal casing.
20. The method according to claim 19, wherein the film is adhered
to surfaces of the longest mat by continuously winding the film
once around the longest mat in a direction perpendicular to a
longitudinal direction of the longest mat, the longest mat is made
to have a winding start position and a winding end position on a
partly exposed main surface, and the winding start position and the
winding end position are spaced apart from each other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119 to Japanese Patent Application No. 2013-117145, filed
Jun. 3, 2013. The contents of this application are incorporated
herein by reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a holding sealing material,
an exhaust gas purifying apparatus, and a method for manufacturing
the exhaust gas purifying apparatus.
[0004] 2. Discussion of the Background
[0005] Exhaust gases discharged from internal combustion engines
(e.g., diesel engines) contain particulate matter (hereinafter,
referred to also as PM). In recent years, the PM has been a problem
as it is harmful to the environment and the human body. Since
exhaust gases also contain harmful gas components such as CO, HC
and NO.sub.x, the influence of the harmful gas components on the
environment and the human body has also been concerned.
[0006] Therefore, various exhaust gas purifying apparatuses for
collecting PM in exhaust gases and purifying the harmful gas
components have been developed. Such exhaust gas purifying
apparatuses include those having an exhaust gas treating body
formed from a porous ceramic material (e.g., silicon carbide,
cordierite), a metal casing for accommodating the exhaust gas
treating body, and a holding sealing material including inorganic
fibers and provided between the exhaust gas treating body and the
metal casing. The holding sealing material is disposed mainly to,
for example, prevent the exhaust gas treating body from breaking
upon contact with the metal casing surrounding the exhaust gas
treating body because of vibration or shocks caused by factors such
as driving of the vehicle, and prevent leakage of exhaust gases
from between the exhaust gas treating body and the metal
casing.
[0007] Here, the internal combustion engine, driven under the
conditions close to the theoretical air fuel ratio to improve the
fuel economy, is likely to produce higher-temperature,
higher-pressure exhaust gases. When the holding sealing material is
exposed to such exhaust gases, the inorganic fibers constituting
the holding sealing material may deteriorate because of the heat.
The holding sealing material is therefore required to have
excellent heat resistance. Also, when high-temperature,
high-pressure exhaust gases reach the exhaust gas purifying
apparatus, the gap between the exhaust gas treating body and the
metal casing may change depending on the difference in the
coefficient of thermal expansion between these components.
Therefore, the holding sealing material is required to also have
the holding power (expansion pressure power) with which it can
sufficiently hold an exhaust gas treating body even when such a
change in the gap occurs. The holding sealing material is also
required to have sufficient sealability for preventing leakage of
exhaust gases from between the exhaust gas treating body and the
metal casing.
[0008] The inorganic fibers constituting the holding sealing
material includes a large number of scratchy fine inorganic fibers
(e.g. fibers having a diameter of from about 3 .mu.m to about 8
.mu.m). In manufacture of an exhaust gas treating body using this
holding sealing material, the inorganic fibers may unfortunately be
scattered from the holding sealing material when the worker deals
with the holding sealing material, which may deteriorate the work
environment.
[0009] Furthermore, when winding the holding sealing material
around the exhaust gas treating body, the outer surface of the
holding sealing material may be ripped. Fine inorganic fibers may
be scattered also from such a rip.
[0010] JP 2003-129832 A discloses a double-layer holding sealing
material formed by a mat that is made of ceramic fibers and
arranged to face the exhaust gas treating body, and a mat that is
made of ceramic fibers and arranged to face the metal casing.
[0011] The holding sealing material disclosed in JP 2003-129832 A
has a mat having excellent heat resistance and facing the exhaust
gas treating body of which the temperature becomes high, and a mat
having excellent flexibility facing the metal casing. This
structure prevents deformation and quality deterioration of the
holding sealing material, and improves the contact of the holding
sealing material with the exhaust gas treating body and the metal
casing.
[0012] Also in the holding sealing material disclosed in JP
2003-129832 A, the mat arranged to face the exhaust gas treating
body with a small radius of curvature has a shorter length in the
longitudinal direction than the mat arranged to face the metal
casing with a large radius of curvature. This structure eliminates
the gap in the engaging portion of the holding sealing material
wound around the exhaust gas treating body, improving the
sealability.
[0013] Furthermore, the holding sealing material of JP 2003-129832
A is sealed by an airtight sheet, so that the ceramic fibers are
prevented from damage, and assembling of the holding sealing
material with the metal casing is facilitated.
[0014] JP 2010-101308 A discloses a holding sealing material
accommodated in the space in a packaging material to reduce
scattering of inorganic fibers from the holding sealing
material.
[0015] JP 2001-521847 A discloses a holding sealing material that
has a flexible sheet or coating on the outer surface thereof to
prevent rips in the outer surface thereof when the holding sealing
material is assembled with the exhaust gas treating body.
SUMMARY OF THE INVENTION
[0016] According to one aspect of the present invention, a holding
sealing material includes a laminate of a plurality of mats and a
film. The plurality of mats each include inorganic fibers and have
a rectangular shape in a plan view. The plurality of mats are
arranged in an order of longitudinal length from a shortest
longitudinal length to a longest longitudinal length. The film is
provided around a longest mat having the longest longitudinal
length among the plurality of mats. The longest mat has a first
main surface and a second main surface which is on a side opposite
to the first main surface and which is in contact with a second
longest mat. The film is adhered to the first main surface and
longitudinal side surfaces of the longest mat and is adhered to the
second main surface to allow the second main surface to be partly
exposed.
[0017] According to another aspect of the present invention, an
exhaust gas purifying apparatus includes an exhaust gas treating
body, a metal casing, and a holding sealing material. The metal
casing accommodates the exhaust gas treating body. The holding
sealing material is placed between the exhaust gas treating body
and the metal casing. The holding sealing material includes a
laminate of a plurality of mats and a film. The plurality of mats
each include inorganic fibers and have a rectangular shape in a
plan view. The plurality of mats are arranged in an order of
longitudinal length from a shortest longitudinal length to a
longest longitudinal length. A longest mat having the longest
longitudinal length among the plurality of mats faces the metal
casing. A shortest mat having the shortest longitudinal length
among the plurality of mats faces the exhaust gas treating body.
The film is provided around the longest mat. The longest mat has a
first main surface and a second main surface which is on a side
opposite to the first main surface and which is in contact with a
second longest mat. The film is adhered to the first main surface
and longitudinal side surfaces of the longest mat and is adhered to
the second main surface to allow the second main surface to be
partly exposed.
[0018] According to further aspect of the present invention, in a
method for manufacturing an exhaust gas purifying apparatus, a
plurality of mats each including inorganic fibers and having a
rectangular shape in a plan view are provided. The plurality of
mats are arranged in an order of longitudinal length from a
shortest longitudinal length to a longest longitudinal length to
form a laminate. A film is adhered around a longest mat having the
longest longitudinal length among the plurality of mats. The film
is adhered to both main surfaces and longitudinal side surfaces of
the longest mat. Part of one of the main surfaces is exposed. The
one of the main surfaces is in contact with a second longest mat.
The laminate of the plurality of mats is wound around an exhaust
gas treating body so that a shortest mat having the shortest
longitudinal length faces the exhaust gas treating body. The
exhaust gas treating body with the laminate of the plurality of
mats is press-fitted into a metal casing so that the longest mat
faces the metal casing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings.
[0020] FIG. 1 is a cross-sectional view schematically illustrating
one example of the exhaust gas purifying apparatus of an embodiment
of the present invention.
[0021] FIG. 2A is a perspective view schematically illustrating one
example of the holding sealing material of an embodiment of the
present invention. FIG. 2B is a perspective view schematically
illustrating one example of an upper layer mat constituting the
holding sealing material of an embodiment of the present invention.
FIG. 2C is a perspective view schematically illustrating one
example of a lower layer mat constituting the holding sealing
material of an embodiment of the present invention.
[0022] FIG. 3A is an enlarged schematic cross-sectional view taken
in the direction perpendicular to the longitudinal length of an
exhaust gas treating body having a holding sealing material wound
therearound, which illustrates the portion where the ends of the
holding sealing material including an upper layer mat and a lower
layer mat having substantially the same full length meet. FIG. 3B
is an enlarged schematic cross-sectional view taken in the
direction perpendicular to the longitudinal direction of an exhaust
gas treating body having the holding sealing material of an
embodiment of the present invention wound therearound, which
illustrates the portion where the ends of the holding sealing
material of an embodiment of the present invention meet.
[0023] FIG. 4 is a cross-sectional view taken along the A-A line in
FIG. 2A.
[0024] FIGS. 5A to 5C each schematically illustrate one example of
the shape of a film to be adhered to the holding sealing material
of an embodiment of the present invention.
[0025] FIG. 6 is a perspective view schematically illustrating one
example of an exhaust gas treating body constituting the exhaust
gas purifying apparatus of an embodiment of the present
invention.
[0026] FIG. 7 is a perspective view schematically illustrating one
example of the process of accommodating the exhaust gas treating
body having the holding sealing material of an embodiment of the
present invention wound therearound into a metal casing.
[0027] FIGS. 8A to 8C are each a schematic cross-sectional view
taken in the direction perpendicular to the longitudinal direction
of the holding sealing material of a comparative example of an
embodiment of the present invention.
[0028] FIG. 9A is a photograph showing the state where the exhaust
gas treating body around which the holding sealing material of an
embodiment of the present invention is wound has been normally
press-fitted into the metal casing. FIG. 9B is a photograph showing
the state where when the exhaust gas treating body around which the
holding sealing material formed by a laminate of mats is wound is
press-fitted, the mats constituting the holding sealing material
are dislocated relative to each other, and the dislocated mats are
protruding from the end of the metal casing.
DESCRIPTION OF THE EMBODIMENTS
[0029] The embodiments will now be described with reference to the
accompanying drawings, wherein like reference numerals designate
corresponding or identical elements throughout the various
drawings.
[0030] The holding sealing material of the embodiment of the
present invention includes a laminate of a plurality of mats each
containing inorganic fibers and having a rectangular shape in a
plan view, the mats arranged in the order of longitudinal length
from the shortest to the longest; and a film adhered to a first
main surface and longitudinal side surfaces of the mat with the
longest longitudinal length among the mats of the laminate, the
first main surface being on the side opposite to a second main
surface which is in contact with the next longest mat, the film
adhered to the second main surface to allow the second main surface
to be partly exposed.
[0031] The holding sealing material of the embodiment of the
present invention is typically used for an exhaust gas purifying
apparatus which is configured to include an exhaust gas treating
body, a metal casing accommodating the exhaust gas treating body,
and a holding sealing material disposed between the exhaust gas
treating body and the metal casing. The holding sealing material of
the embodiment of the present invention is wound around the exhaust
gas treating body, and the exhaust gas treating body around which
the holding sealing material of the embodiment of the present
invention is wound is accommodated into the metal casing.
[0032] The holding sealing material of the embodiment of the
present invention includes a laminate of a plurality of mats each
containing inorganic fibers and having a rectangular shape in a
plan view, the mats arranged in the order of longitudinal length
from the shortest to the longest.
[0033] The holding sealing material of the embodiment of the
present invention is typically wound around the exhaust gas
treating body so that the mat having the shortest length in the
longitudinal direction comes into contact with the exhaust gas
treating body. Hence, among the mats of the holding sealing
material wound around the exhaust gas treating body, the mat in
contact with the exhaust gas treating body has the shortest length,
and the other mats each have a longer length than the next inner
mat. Accordingly, when the holding sealing material of the
embodiment of the present invention is wound around the exhaust gas
treating body, a gap attributed to the different inner and outer
peripheries is hardly generated in the portion where the ends of
the holding sealing material meet. The exhaust gas purifying
apparatus including the holding sealing material of the embodiment
of the present invention therefore has sufficient sealability for
preventing exhaust gas leakage.
[0034] The holding sealing material of the embodiment of the
present invention includes a film adhered to a first main surface
and longitudinal side surfaces of the mat with the longest
longitudinal length among the mats of the laminate, the first main
surface being on the side opposite to a second main surface which
is in contact with the next longest mat.
[0035] The surface of the mat is the part from which inorganic
fibers are scattered. In particular, the mat constituting the
outermost layer of the laminate is placed in the position of the
largest radius of curvature, and thus receives the largest tensile
stress when the holding sealing material is wound around the
exhaust gas treating body. The tensile stress causes the inorganic
fibers to be easily torn. As a result, a defect such as a rip is
generated in the surface of the mat, and thus the inorganic fibers
are likely to be scattered.
[0036] However, if a film is adhered to the mat as in the case of
the holding sealing material of the embodiment of the present
invention, such scattering of inorganic fibers can be reduced.
[0037] Scattering of inorganic fibers occurs not only from the main
surfaces of the holding sealing material but also from the
longitudinal side surfaces of the holding sealing material. The
longitudinal side surfaces are surfaces located at parts
constituting the long sides of the rectangle in a plan view of the
mat. In particular, when the exhaust gas treating body around which
the holding sealing material is wound is press-fitted into the
metal casing, the holding sealing material is compressed in the
thickness direction. The holding sealing material is therefore
likely to discharge air from the longitudinal side surfaces. The
discharging air leads to scattering of inorganic fibers. Such
scattering of inorganic fibers from the longitudinal side surfaces
of the holding sealing material is not negligible from the
viewpoint of improvement in the work environment.
[0038] The holding sealing material of the embodiment of the
present invention includes a film adhered to the longitudinal side
surfaces of the mat having the longest longitudinal length. This
structure reduces scattering of inorganic fibers from the parts to
which a film is adhered. Accordingly, scattering of inorganic
fibers can be reduced in dealing with the holding sealing material
of the embodiment of the present invention.
[0039] If the main surface of the mat having the longest
longitudinal length in contact with the mat of the lower layer
(hereinafter, also referred to as the second main surface) is
completely covered with a film, the contact between the mat with
the longest longitudinal length and the next longest mat in contact
with the longest mat decreases. Hence, when the exhaust gas
treating body around which the holding sealing material having the
above structure is wound is press-fitted into the metal casing, the
mat with the longest longitudinal length and the next longest mat
in contact with the longest mat are likely to be dislocated
relative to each other. As a result, the dislocated mat is likely
to protrude from the end of the metal casing. In the holding
sealing material of the embodiment of the present invention,
however, the film is adhered to the second main surface of the mat
with the longest longitudinal length, so that the second main
surface is partly exposed. The exposed part allows the mat with the
longest longitudinal length to come into direct contact with the
next longest mat. That is, at this part, the inorganic fibers
contained in the mats are in direct contact and are thus entangled,
whereby the contact between the mats increases. Furthermore, since
the inorganic fibers are rubbed against each other, the mat with
the longest longitudinal length and the next longest mat in contact
with the longest mat are not likely to be dislocated relative to
each other when the exhaust gas treating body around which the
holding sealing material of the embodiment of the present invention
is wound is press-fitted into the metal casing. Therefore,
protrusion of the mat from the end of the metal casing can be
prevented.
[0040] In the holding sealing material of the embodiment of the
present invention, preferably, the film adhered to the surfaces of
the mat with the longest longitudinal length is continuously wound
once around the mat in the direction perpendicular to the
longitudinal direction of the mat, the mat with the longest
longitudinal length has a winding start position and a winding end
position on the second main surface, and the winding start position
and the winding end position are spaced apart from each other.
[0041] Here, winding once means that, in the state where the
winding start position and the winding end position exist on the
same main surface, winding starts from the winding start position,
passes through the side surface closer to the winding start
position, the main surface opposite to the main surface where the
winding start position and the winding end position exist, and the
side surface closer to the winding end position, and then ends at
the winding end position when the winding comes to the winding end
position for the first time.
[0042] The expression of being "spaced apart" means that the
winding start position and the winding end position are apart from
each other, so that the film does not exist between these
positions.
[0043] The film adhered to the holding sealing material having the
above structure is seamless. Accordingly, scattering of inorganic
fibers from seams of the film does not occur. Scattering of
inorganic fibers from the holding sealing material can therefore be
reduced.
[0044] The parts of the film adhered to the second main surface of
the mat with the longest longitudinal length are sandwiched between
the mat with the longest longitudinal length and the next longest
mat in contact with the longest mat. This structure prevents
peeling of the film.
[0045] In the holding sealing material of the embodiment of the
present invention, the laminate of the plurality of mats preferably
consists of two mats.
[0046] If the laminate includes three or more mats, the laminate
has a bulky size which increases the working step and thus makes it
difficult to handle the holding sealing material efficiently in
production of the holding sealing material or winding of the
holding sealing material around the exhaust gas treating body. If,
however, the laminate as the holding sealing material includes two
mats, manufacture of the holding sealing material is easy. The
structure also facilitates handling of the holding sealing material
when the holding sealing material is transferred or when the
holding sealing material is wound around the exhaust gas treating
body.
[0047] In the holding sealing material of the embodiment of the
present invention, the film preferably includes at least one
material selected from the group consisting of polyester,
high-density polyethylene, and polypropylene.
[0048] As described above, the holding sealing material of the
embodiment of the present invention is usually wound around the
exhaust gas treating body, and then press-fitted into the metal
casing. At this time, the mat constituting the outermost layer of
the laminate and with the longest longitudinal length comes into
contact with the metal casing via the film.
[0049] If the film includes at least one material selected from the
group consisting of polyester, high-density polyethylene, and
polypropylene, the coefficient of friction between the mat and
metal casing is small. Therefore, the exhaust gas treating body
around which the holding sealing material of the embodiment of the
present invention is wound can be press-fitted smoothly into the
metal casing.
[0050] In the holding sealing material of the embodiment of the
present invention, the film is preferably fixed on the laminate of
the plurality of mats with an adhesive or by thermocompression
bonding.
[0051] Using an adhesive or thermocompression bonding, the film can
be firmly fixed to the holding sealing material.
[0052] In the holding sealing material of the embodiment of the
present invention, the plurality of mats of the laminate are
preferably bound by at least one band having no fixing
strength.
[0053] In the holding sealing material having the above structure,
the mats are not fixed to each other, and thus the mats can be
moved in the longitudinal direction when the holding sealing
material is wound around the exhaust gas treating body.
[0054] Accordingly, even when the mats are dislocated relative to
each other, the relative positions of the mats can be finely
adjusted when the holding sealing material is wound around the
exhaust gas treating body. As a result, a gap is less likely to be
formed at a part where the ends of the holding sealing material
meet.
[0055] In the holding sealing material of the embodiment of the
present invention, the band is preferably made of paper or
resin.
[0056] Paper or resin can be suitably used as a band having no
fixing strength to the surface of the mat.
[0057] In the holding sealing material of the embodiment of the
present invention, the plurality of mats of the laminate are
preferably fixed to each other at at least one fixed part.
[0058] When the mats are fixed to each other at at least one fixed
part, the mats are not separated from each other, and thereby it is
easier to handle the holding sealing material. Also, the holding
sealing material can be easily wound around the exhaust gas
treating body without separately positioning the mats.
[0059] In the holding sealing material of the embodiment of the
present invention, the fixed part preferably exists along the
direction perpendicular to the longitudinal direction of the
laminate of the plurality of mats.
[0060] If the fixed part extends in the direction perpendicular to
the longitudinal direction of the holding sealing material, the
mats can be prevented from moving in the direction perpendicular to
the longitudinal direction of the holding sealing material when the
holding sealing material is wound around the exhaust gas treating
body.
[0061] Also, if the fixed part exists along the direction parallel
to the longitudinal direction of the holding sealing material,
tensile stress tends to be generated in the outer peripheral
portion of the holding sealing material, and wrinkles tend to be
generated in the inner peripheral portion of the holding sealing
material. This structure causes to generate a gap between the
holding sealing material and the exhaust gas treating body.
However, if the fixed part extends in the direction perpendicular
to the longitudinal direction of the holding sealing material,
generation of such tensile stress or wrinkles can be prevented, so
that a gap does not easily form between the holding sealing
material and the exhaust gas treating body.
[0062] In the holding sealing material of the embodiment of the
present invention, the fixed part is preferably made of thread,
pressure-sensitive adhesive tape, or an adhesive.
[0063] Thread, pressure-sensitive adhesive tape, or an adhesive can
be suitably used as the fixed part for fixing the mats.
[0064] The exhaust gas purifying apparatus of the embodiment of the
present invention includes: an exhaust gas treating body, a metal
casing accommodating the exhaust gas treating body, and a holding
sealing material placed between the exhaust gas treating body and
the metal casing, the holding sealing material containing a
laminate of a plurality of mats each containing inorganic fibers
and having a rectangular shape in a plan view, the mats arranged in
the order of longitudinal length from the shortest to the longest,
the mat with the longest longitudinal length among the mats of the
laminate facing the metal casing, the mat with the shortest
longitudinal length among the mats of the laminate facing the
exhaust gas treating body, the holding sealing material including a
film adhered to a first main surface and longitudinal side surfaces
of the mat with the longest longitudinal length among the mats of
the laminate, the first main surface being on the side opposite to
a second surface which is in contact with the next longest mat, the
film adhered to the second main surface to allow the second main
surface to be partly exposed.
[0065] The exhaust gas purifying apparatus of the embodiment of the
present invention including the holding sealing material of the
embodiment of the present invention can achieve the above
effects.
[0066] In the exhaust gas purifying apparatus of the embodiment of
the present invention, preferably, the film adhered to the surfaces
of the mat with the longest longitudinal length is continuously
wound once around the mat in the direction perpendicular to the
longitudinal direction of the mat, the mat with the shortest
longitudinal length has a winding start position and a winding end
position on the second main surface, and the winding start position
and the winding end position are spaced apart from each other.
[0067] In the exhaust gas purifying apparatus having the above
structure, the film adhered to the holding sealing material is
seamless. Accordingly, scattering of inorganic fibers from seams of
the film does not occur. Scattering of inorganic fibers from the
holding sealing material can therefore be reduced when the exhaust
gas purifying apparatus is manufactured, for example.
[0068] The method for manufacturing an exhaust gas purifying
apparatus according to the embodiment of the present invention is a
method for manufacturing the exhaust gas purifying apparatus
including an exhaust gas treating body, a metal casing
accommodating the exhaust gas treating body, and a holding sealing
material placed between the exhaust gas treating body and the metal
casing, the holding sealing material containing a laminate of a
plurality of mats each containing inorganic fibers and having a
rectangular shape in a plan view, the mats arranged in the order of
longitudinal length from the shortest to the longest, the mat with
the longest longitudinal length among the mats of the laminate
facing the metal casing, the mat with the shortest longitudinal
length among the mats of the laminate the exhaust gas treating
body. The method includes: adhering a film to both main surfaces
and longitudinal side surfaces of the mat with the longest
longitudinal length to allow part of one of the main surfaces to be
exposed; forming the laminate of the plurality of mats by arranging
the mats in the order of longitudinal length from the shortest to
the longest by bringing the exposed main surface of the longest mat
as a top layer in contact with the next longest mat; winding the
laminate of the plurality of mats around the exhaust gas treating
body by allowing the mat with the longest longitudinal length to
face the metal casing and allowing the mat with the shortest
longitudinal length to face the exhaust gas treating body; and
press-fitting the exhaust gas treating body with the laminate of
the plurality of mats wound therearound into the metal casing.
[0069] The method for manufacturing the exhaust gas purifying
apparatus of the embodiment of the present invention using the
above holding sealing material of the embodiment of the present
invention can achieve the above effects.
[0070] In the method for manufacturing an exhaust gas purifying
apparatus according to the embodiment of the present invention,
preferably, the film is adhered to the surfaces of the mat with the
longest longitudinal length by continuously winding the film once
around the mat in the direction perpendicular to the longitudinal
direction of the mat, the mat with the longest longitudinal length
is made to have a winding start position and a winding end position
on the partly exposed main surface, and the winding start position
and the winding end position are spaced apart from each other.
[0071] Adhesion of a film in this manner enables adhesion of the
film to the main surfaces and longitudinal side surfaces of the mat
such that part of one of the main surfaces of the mat with the
longest longitudinal length is exposed in one step. Accordingly,
the film can be adhered efficiently.
[0072] Also, adhesion of a film in this manner enables adhesion of
the film without seams. With such a seamless film, scattering of
inorganic fibers from seams of the film does not occur. Scattering
of inorganic fibers can be reduced in the winding of the laminate
of the mats around the exhaust gas treating body and in the
press-fitting of the exhaust gas treating body with the laminate of
the mats wound therearound into the metal casing.
[0073] Hereafter, the embodiment of the present invention is
described in detail. The present invention, however, is not limited
by the following description, and appropriate changes may be made
without departing from the scope of the present invention. The
present invention also encompasses combinations of structures of
the embodiment of the present invention described below.
[0074] FIG. 1 is a cross-sectional view schematically illustrating
one example of the exhaust gas purifying apparatus of the
embodiment of the present invention.
[0075] As illustrated in FIG. 1, an exhaust gas purifying apparatus
1, which is one example of the exhaust gas purifying apparatus of
the embodiment of the present invention, includes an exhaust gas
treating body 10, a metal casing 20 covering the outer side of the
exhaust gas treating body 10, and a holding sealing material 30
placed between the exhaust gas treating body 10 and the metal
casing 20. To the end of the metal casing 20 from which exhaust
gases are introduced, an inlet pipe 21 connected to an internal
combustion engine (e.g., gasoline engine) is coupled. To the other
end of the metal casing 20, an outlet pipe 22 connected to the
outside is coupled.
[0076] In the exhaust gas purifying apparatus 1 illustrated in FIG.
1, the exhaust gas treating body 10 is an exhaust gas filter
(honeycomb filter) in which either one end of each cell is sealed
by a plug 13.
[0077] Passage of exhaust gases through the exhaust gas purifying
apparatus 1 having the above structure is described below with
reference to FIG. 1.
[0078] As illustrated in FIG. 1, exhaust gases discharged from the
internal combustion engine and flown into the exhaust gas purifying
apparatus 1 (in FIG. 1, exhaust gases are indicated by G, and the
flow of the exhaust gases is indicated by the arrows) are flown
into cells 11 which are open at an exhaust gas inlet-side end 10a
of the exhaust gas treating body 10. Exhaust gases flown into one
of the cells 11 pass through cell walls 21 separating the cells 11.
At this time, PM in the exhaust gasses is captured by the cell
walls 12, so that the exhaust gases are purified. The purified
exhaust gases flow out from the other cells 11, which are open at
the exhaust gas outlet-side end 10b, so as to be discharged to the
outside.
[0079] Next, the holding sealing material 30 of the embodiment of
the present invention is described.
[0080] FIG. 2A is a perspective view schematically illustrating one
example of the holding sealing material of the embodiment of the
present invention. FIG. 2B is a perspective view schematically
illustrating one example of an upper layer mat constituting the
holding sealing material of the embodiment of the present
invention. FIG. 2C is a perspective view schematically illustrating
one example of a lower layer mat constituting the holding sealing
material of the embodiment of the present invention.
[0081] The holding sealing material 30 of the embodiment of the
present invention illustrated in FIG. 2A is a laminate of two mats,
namely an upper layer mat 40 and a lower layer mat 50, each
including inorganic fibers and having a substantially rectangular
shape in a plan view with a predetermined longitudinal length (also
referred to simply as a full length; indicated by the arrow L in
FIG. 2A), a predetermined width (indicated by the arrow W in FIG.
2A), and a predetermined thickness (indicated by the arrow T in
FIG. 2A).
[0082] The upper layer mat 40 has a first main surface 41 not in
contact with the lower layer mat 50, and a second main surface 42
which is on the side opposite to the first main surface 41 and is
in contact with the lower layer mat 50. The upper layer mat 40
includes an end 43 at which a projected portion 43a is formed, an
end 44 at which a recessed portion 44a is formed, a first side
surface 45 that is a longitudinal side surface, and a second side
surface 46 that is on the side opposite to the first side surface
45. The longitudinal side surface is a surface located at a part
constituting a long side of the rectangle in a plan view of the
upper layer mat 40. The projected portion 43a and the recessed
portion 44a have shapes that allow the projected portion 43a and
the recessed portion 44a to fit each other when the holding sealing
material 30 is wound around the exhaust gas treating body 10 for
assembly of the exhaust gas purifying apparatus 1.
[0083] The lower layer mat 50 has a first main surface 51 in
contact with the upper layer mat 40, and a second main surface 52
which is on the side opposite to the first main surface 51 and is
not in contact with the upper layer mat 40. The lower layer mat 50
includes an end 53 at which a projected portion 53a is formed, an
end 54 at which a recessed portion 54a is formed, a first side
surface 55 that is a longitudinal side surface, and a second side
surface 56 that is on the side opposite to the first side surface
55. The longitudinal side surface is a surface located at a part
constituting a long side of the rectangle in a plan view of the
lower layer mat 50. The projected portion 53a and the recessed
portion 54a have shapes that allow the projected portion 53a and
the recessed portion 54a to fit each other when the holding sealing
material 30 is wound around the exhaust gas treating body 10 for
assembly of the exhaust gas purifying apparatus 1.
[0084] In the exhaust gas purifying apparatus 1 of the embodiment
of the present invention, the upper layer mat 40 is placed to face
the metal casing 20, and the lower layer mat 50 is placed to face
the exhaust gas treating body 10.
[0085] In the holding sealing material 30 of the embodiment of the
present invention, the full length of the upper layer mat 40 is
made longer than the full length of the lower layer mat 50 such
that a gap is not formed between the ends of the holding sealing
material 30 when the holding sealing material 30 is wound around
the exhaust gas treating body 10. This structure is described based
on FIGS. 3A and 3B.
[0086] FIG. 3A is an enlarged schematic cross-sectional view taken
in the direction perpendicular to the longitudinal length of an
exhaust gas treating body having a holding sealing material wound
therearound, which illustrates the portion where the ends of the
holding sealing material including an upper layer mat and a lower
layer mat having substantially the same full length meet. FIG. 3B
is an enlarged schematic cross-sectional view taken in the
direction perpendicular to the longitudinal direction of an exhaust
gas treating body having the holding sealing material of the
embodiment of the present invention wound therearound, which
illustrates the portion where the ends of the holding sealing
material of the embodiment of the present invention meet.
[0087] As illustrated in FIG. 3A, when an upper layer mat 40' and a
lower layer mat 50' constituting a holding sealing material 30'
have substantially the same full length, a gap is formed because of
the different inner and outer peripheries when the holding sealing
material 30' is wound around the exhaust gas treating body 10'.
That is, an end 53' and an end 54' of the lower layer mat 50' fit
each other substantially without a gap, but a gap is formed between
an end 43' and an end 44' of the upper layer mat 40' because of the
different inner and outer peripheries.
[0088] In contrast, as illustrated in FIG. 3B, the full length of
the upper layer mat 40 constituting the holding sealing material 30
of the embodiment of the present invention is longer than the full
length of the lower layer mat 50 so that the above gap because of
the different inner and outer peripheries is filled. This structure
allows the end 43 and the end 44 of the upper layer mat 40 to fit
each other substantially without a gap when the holding sealing
material 30 is wound around the exhaust gas treating body 10.
[0089] The exhaust gas purifying apparatus 1 including the holding
sealing material 30 of the embodiment of the present invention
therefore has sufficient sealability for preventing leakage of
exhaust gases. The full length of the upper layer mat 40 is
preferably from about 1.05 times to about 1.10 times the full
length of the lower layer mat 50.
[0090] The upper layer mat 40 and the lower layer mat 50 are each
obtained by needle-punching a base mat made of inorganic fibers.
Here, the needle punching refers to inserting and drawing a
fiber-interlacing tool such as needles into and from the base mat.
In each of the upper layer mat 40 and the lower layer mat 50,
inorganic fibers having a relatively long average fiber length are
three-dimensionally interlaced by needle punching. These mats are
each needle-punched in the width direction which is perpendicular
to the longitudinal direction.
[0091] The inorganic fibers may be any inorganic fibers having a
certain average fiber length, for example an average fiber length
of from about 50 .mu.m to about 100 mm, for forming an interlaced
structure.
[0092] The inorganic fibers constituting each of the upper layer
mat 40 and the lower layer mat 50 preferably have an average fiber
diameter of from about 1 .mu.m to about 20 .mu.m, more preferably
from about 3 .mu.m to about 10 .mu.m. An average fiber diameter of
the inorganic fibers of from about 1 .mu.m to about 20 .mu.m may
sufficiently increase the strength and flexibility of the inorganic
fibers. Therefore, the shear strength of the upper layer mat 40 and
the lower layer mat 50 increases.
[0093] An average fiber diameter of the inorganic fibers of smaller
than about 1 .mu.m may make the inorganic fibers thin and easily
breakable to give insufficient tensile strength to the inorganic
fibers. An average fiber diameter of the inorganic fibers of
greater than about 20 .mu.m may not allow the inorganic fibers to
easily bend, giving insufficient flexibility to the fibers.
[0094] The basis weight (weight per unit area) of each of the upper
layer mat 40 and the lower layer mat 50 is not particularly
limited, but is preferably from about 200 g/m.sup.2 to about 4000
g/m.sup.2, and more preferably from about 1000 g/m.sup.2 to about
3000 g/m.sup.2. A basis weight of less than about 200 g/m.sup.2 may
not provide sufficient holding strength to each of the upper layer
mat 40 and the lower layer mat 50. Therefore, when the exhaust gas
purifying apparatus 1 is manufactured using these upper layer mat
40 and the lower layer mat 50, the exhaust gas treating body 10
tends to come off. A basis weight of more than about 4000 g/m.sup.2
makes it difficult to reduce the bulky size of the upper layer mat
40 and the lower layer mat 50.
[0095] The bulk density of each of the upper layer mat 40 and the
lower layer mat 50 (bulk density of each mat of the holding sealing
material before winding) is not particularly limited either, but is
preferably from about 0.10 g/cm.sup.3 to about 0.30 g/cm.sup.3. A
bulk density of each of the upper layer mat 40 and the lower layer
mat 50 of less than about 0.10 g/cm.sup.3 may have the inorganic
fibers interlaced insufficiently to let the inorganic fibers be
separated, thereby making it difficult to maintain the
predetermined shapes of the upper layer mat 40 and the lower layer
mat 50.
[0096] A bulk density of each of the upper layer mat 40 and the
lower layer mat 50 of more than about 0.30 g/cm.sup.3 may make the
upper layer mat 40 and the lower layer mat 50 stiff to decrease the
winding property for the exhaust gas treating body 10, causing
breakage of each mat easily.
[0097] For reduction of the bulky size or improvement of the
workability before assembly of the exhaust gas purifying apparatus
1, each of the upper layer mat 40 and the lower layer mat 50 may
further contain a binder such as an organic binder.
[0098] The thickness of each of the upper layer mat 40 and the
lower layer mat 50 is preferably from about 1.5 mm to about 15
mm.
[0099] FIG. 4 is a cross-sectional view taken along the A-A line in
FIG. 2A.
[0100] As illustrated in FIG. 4, a film 60 is adhered to the
holding sealing material 30. The film 60 adhered is one sheet, and
is continuously wound once around the upper layer mat 40 in the
direction perpendicular to the longitudinal direction of the upper
layer mat 40 from a winding start position 47 to a winding end
position 48 which are on the second main surface 42. That is, the
film 60 is continuously wound around the upper layer mat 40 from
the winding start position 47 as a start position of winding to the
winding end position 48 which are on the second main surface 42,
along the second main surface 42, the first side surface 45, the
first main surface 41, the second side surface 46, and the second
main surface 42. The winding start position 47 and the winding end
position 48 are apart from each other such that part of the second
main surface 42 of the upper layer mat 40 is exposed.
[0101] In the holding sealing material 30 of the embodiment of the
present invention, the film 60 is adhered to the second main
surface 42 of the upper layer mat 40, so that the second main
surface 42 is partly exposed. The exposed part allows the second
main surface 42 of the upper layer mat 40 to come into direct
contact with the first main surface 51 of the lower layer mat 50.
That is, at this part, the inorganic fibers contained in the mats
are in direct contact and are thus entangled, whereby the contact
between the upper layer mat 40 and the lower layer mat 50
increases. Furthermore, since the inorganic fibers contained in the
mats are rubbed against each other, the mats are not likely to be
dislocated relative to each other when the exhaust gas treating
body 10 around which the holding sealing material 30 of the
embodiment of the present invention is wound is press-fitted into
the metal casing 20. Therefore, protrusion of the upper layer mat
40 from the end of the metal casing 20 can be prevented.
[0102] The area where the first main surface 51 of the lower layer
mat 50 is in direct contact with the second main surface 42 of the
upper layer mat 40 is preferably from about 40% to about 90%, more
preferably from about 80% to about 90%, of the entire area of the
first main surface 51 of the lower layer mat 50. The area in the
above range enables sufficient prevention of dislocation of the
mats relative to each other.
[0103] The mat 60 is adhered to the first main surface 41 of the
upper layer mat 40.
[0104] When the holding sealing material 30 is wound around the
exhaust gas treating body 10, the upper layer mat 40 comes to an
outer position than the lower layer mat 50. As a result, the upper
layer mat 40 has a larger radius of curvature than the lower layer
mat 50, and thus receives larger tensile stress.
[0105] The tensile stress causes the inorganic fibers to be easily
torn. As a result, a defect such as a rip is generated in the first
main surface 41 of the upper layer mat 40, and thus the inorganic
fibers are likely to be scattered.
[0106] However, the film 60 is adhered to the mat of the holding
sealing material 30 of the embodiment of the present invention.
Accordingly, scattering of inorganic fibers from the first main
surface 41 can be reduced.
[0107] The film 60 is adhered to the first side surface 45 and the
second side surface 46 of the upper layer mat 40 in the holding
sealing material 30 of the embodiment of the present invention.
[0108] Scattering of inorganic fibers of the holding sealing
material 30 occurs not only from the first main surface 41 of the
upper layer mat 40 but also from the first and second side surfaces
45 and 46 of the upper layer mat 40.
[0109] In particular, when the exhaust gas treating body 10 around
which the holding sealing material 30 is wound is press-fitted into
the metal casing 20, the holding sealing material 30 is compressed
in the thickness direction. The holding sealing material 30 is
therefore likely to discharge air from the first and second side
surfaces 45 and 46 of the upper layer mat 40. The discharging air
leads to scattering of inorganic fibers.
[0110] The holding sealing material 30 of the embodiment of the
present invention includes the film 60 adhered to the first and
second side surfaces 45 and 46 of the upper layer mat 40 as
described above. This structure reduces scattering of inorganic
fibers from the parts to which the film 60 is adhered. Accordingly,
scattering of inorganic fibers can be reduced in dealing with the
holding sealing material 30 of the embodiment of the present
invention.
[0111] As described above, the film 60 is one sheet, and is
continuously wound once around the upper layer mat 40 from the
winding start position 47 to the winding end position 48 which are
on the second main surface 42 of the upper layer mat 40, in the
direction perpendicular to the longitudinal direction of the upper
layer mat 40. The film 60 adhered is thus seamless. Accordingly,
scattering of inorganic fibers from seams of the film does not
occur. Scattering of inorganic fibers from the holding sealing
material 30 can therefore be reduced.
[0112] The parts of the film 60 adhered to the second main surface
42 of the upper layer mat 40 are sandwiched between the upper layer
mat 40 and the lower layer mat 50. This structure prevents peeling
of the film 60.
[0113] FIGS. 5A to 5C each schematically illustrate one example of
the shape of a film to be adhered to the holding sealing material
of the embodiment of the present invention. FIGS. 5A to 5C are each
a perspective view illustrating the state where each film is
adhered to the holding sealing material.
[0114] The shape of the film 60 may be any shape such as those
illustrated in FIGS. 5A to 5C.
[0115] The film 60a illustrated in FIG. 5A has a substantially
rectangular shape with long sides 61a and short sides 62a.
[0116] At one short side 62a of the film 60a, a projected portion
63a is formed.
[0117] When the film 60a is adhered to the upper layer mat 40, the
film 60a is adhered to the upper layer mat 40 so that the projected
portion 63a of the film 60a covers the projected portion 43a of the
upper layer mat 40.
[0118] The film 60b illustrated in FIG. 5B has a substantially
rectangular shape with long sides 61b and short sides 62b.
[0119] At one short side 62b of the film 60b, a recessed portion
64b is formed.
[0120] When the film 60b is adhered to the upper layer mat 40, the
film 60b is adhered to the upper layer mat 40 so that the recessed
portion 64b of the film 60b covers the recessed portion 44a of the
upper layer mat 40.
[0121] The film 60c illustrated in FIG. 5C has a substantially
rectangular shape with long sides 61c and short sides 62c.
[0122] At one short side 62c of the film 60c, a projected portion
63c is formed. At the other short side 62c, a recessed portion 64c
is formed.
[0123] When the film 60c is adhered to the upper layer mat 40, the
film 60c is adhered to the upper layer mat 40 so that the projected
portion 63c of the film 60c covers the projected portion 43a of the
upper layer mat 40, and the recessed portion 64c of the film 60c
covers the recessed portion 44a of the upper layer mat 40.
[0124] In this way, reducing the area not covered by the film 60 on
the upper layer mat 40 enables further reduction of scattering of
inorganic fibers from the upper layer mat 40. Therefore, the shape
of the film 60c is most preferably among these shapes.
[0125] In the holding sealing material 30 of the embodiment of the
present invention, the film 60 is not present on the second main
surface 52 of the lower layer mat 50.
[0126] This structure allows the inorganic fibers contained in the
lower layer mat 50 to come into direct contact with the exhaust gas
treating body 10, and to be entangled with the surface of the
exhaust gas treating body 10. Thereby, the contact between the
lower layer mat 50 and the exhaust gas treating body 10 increases.
As a result, since the inorganic fibers are rubbed against the
exhaust gas treating body 10, the lower layer mat 50 is not likely
to be dislocated relative to the exhaust gas treating body 10 when
the exhaust gas treating body 10 with the holding sealing material
30 wound therearound is press-fitted into the metal casing 20.
Therefore, protrusion of the lower layer mat 50 from the end of the
metal casing 20 can be prevented.
[0127] In the holding sealing material 30 of the embodiment of the
present invention, the film 60 preferably includes at least one
material selected from the group consisting of polyester,
high-density polyethylene, and polypropylene.
[0128] As described above, the holding sealing material 30 of the
embodiment of the present invention is wound around the exhaust gas
treating body 10, and then the exhaust gas treating body 10 is
press-fitted into the metal casing 20. At this time, the upper
layer mat 40 comes into contact with the metal casing 20 via the
film 60.
[0129] When the film 60 includes at least one selected from the
group consisting of polyester, high-density polyethylene, and
polypropylene, the coefficient of friction between the upper layer
mat 40 and the metal casing 20 is small. Hence, the exhaust gas
treating body 10 around which the holding sealing material 30 is
wound can be smoothly press-fitted into the metal casing 20.
[0130] The film 60 for the holding sealing material 30 of the
embodiment of the present invention preferably has a thickness of
from about 30 .mu.m to about 60 .mu.m.
[0131] A thickness of the film 60 of smaller than about 30 .mu.m
may be excessively thin to cause breakage of the film 60.
[0132] A thickness of the film 60 of greater than about 60 .mu.m
may be excessively thick to cause a very large amount of the film
60 to be adhered per unit weight of the inorganic fibers. This may
result in a very large amount of gases such as hydrocarbon gas
generated upon decomposition, though the holding sealing material
can be press-fitted into the casing without problems.
[0133] The film 60 for the holding sealing material 30 of the
embodiment of the present invention is preferably fixed to the
holding sealing material 30 with an adhesive or by
thermocompression bonding.
[0134] Using an adhesive or thermocompression bonding, the film 60
can be firmly fixed to the holding sealing material 30.
[0135] In the holding sealing material 30 of the embodiment of the
present invention, the upper layer mat 40 and the lower layer mat
50 are fixed to each other at two fixed parts 32. The two fixed
parts 32 exist along the direction perpendicular to the
longitudinal direction of the holding sealing material 30.
[0136] When the upper layer mat 40 and the lower layer mat 50 are
fixed to each other at the two fixed parts 32, the mats are not
separated from each other, and thereby the mats are prevented from
being dislocated relative to each other. It is therefore easier to
handle the holding sealing material 30. Also, the holding sealing
material 30 can be easily wound around the exhaust gas treating
body 10 without separately positioning the mats.
[0137] If the two fixed parts 32 exist along the direction
perpendicular to the longitudinal direction of the holding sealing
material 30, the mats can be prevented from moving in the direction
perpendicular to the longitudinal direction of the holding sealing
material 30 when the holding sealing material 30 is wound around
the exhaust gas treating body 10. Also, if the fixed part exists
along the direction parallel to the longitudinal direction of the
holding sealing material, tensile stress tends to be generated in
the outer peripheral portion of the holding sealing material, and
wrinkles tend to be generated in the inner peripheral portion of
the holding sealing material. However, if the fixed part exists
along the direction perpendicular to the longitudinal direction of
the holding sealing material 30, generation of such tensile stress
or wrinkles can be prevented, so that a gap does not easily form
between the holding sealing material 30 and the exhaust gas
treating body 10.
[0138] In the holding sealing material 30 of the embodiment of the
present invention, the distance between the two fixed parts 32 is
preferably from about 1/20 to about 3/4 of the full length of the
mat with the shortest full length, i.e., the lower layer mat
50.
[0139] If the distance between the two fixed parts 32 is shorter
than about 1/20 of the full length of the lower layer mat 50, the
positions of the two fixed parts relative to the entire mat are
concentrated to one small area, which may make it difficult to
prevent dislocation of the mats in the width direction.
[0140] If the distance between the two fixed parts 32 is longer
than about 3/4 of the full length of the lower layer mat 50, the
area between the two fixed parts 32 may be too wide. The ends of
this area are fixed by the two fixed parts 32, and thus distortion
because of different inner and outer peripheries tends to be
generated when the holding sealing material 30 is wound around the
exhaust gas treating body 10. As a result, tensile strength tends
to occur on the upper layer mat 40 side, and wrinkles tend to be
generated on the lower layer mat 50 side.
[0141] The fixed parts 32 for the holding sealing material 30 of
the embodiment of the present invention are each preferably made of
thread, pressure-sensitive adhesive tape, or an adhesive.
[0142] Thread, pressure-sensitive adhesive tape, or an adhesive can
be suitably used as the fixed parts 32 for fixing the mats.
[0143] Next, the exhaust gas treating body 10 constituting the
exhaust gas purifying apparatus 1 of the embodiment of the present
invention is described.
[0144] FIG. 6 is a perspective view schematically illustrating one
example of an exhaust gas treating body constituting the exhaust
gas purifying apparatus of the embodiment of the present
invention.
[0145] As illustrated in FIG. 6, the exhaust gas treating body 10
is made mainly of a porous ceramic material and has a substantially
cylindrical shape. Also, the exhaust gas treating body 10 is
peripherally provided with a peripheral coat layer 14 so that the
peripheral portion of the exhaust gas treating body 10 is
reinforced, the shape of the peripheral portion is arranged, and
the heat insulation of the exhaust gas treating body 10 is
increased.
[0146] The internal structure of the exhaust gas treating body 10
is the same as that described above in description of the exhaust
gas purifying apparatus 1 of the embodiment of the present
invention (c.f. FIG. 1).
[0147] The exhaust gas treating body 10 may be made of non-oxidized
porous ceramics such as silicon carbide and silicon nitride, or may
be made of oxidized porous ceramics such as sialon, alumina,
cordierite, and mullite. Preferably among these is silicon
carbide.
[0148] If the exhaust gas treating body 10 is a silicon carbide
based porous body, the porosity of the exhaust gas treating body is
not particularly limited, but is preferably from about 35% to about
60%.
[0149] A porosity of lower than about 35% may easily cause clogging
in the exhaust gas treating body, while a porosity of higher than
about 60% may decrease the strength of the exhaust gas treating
body to make it easily broken.
[0150] The average pore diameter of the exhaust gas treating body
is preferably from about 5 .mu.m to about 30 .mu.m.
[0151] An average pore diameter of smaller than about 5 .mu.m may
easily cause clogging with PM. An average pore diameter of larger
than about 30 .mu.m may allow PM to pass through the pores to let
the exhaust gas treating body fail to capture PM, disabling the
exhaust gas treating body to function as a filter.
[0152] The above porosity and pore diameter can be measured by
known measurement methods using a scanning electron microscope
(SEM).
[0153] The cell density at a cross section of the exhaust gas
treating body 10 is not particularly limited. Still, the cell
density is preferably from a lower limit of about 31.0 pcs/cm.sup.2
(about 200 pcs/inch.sup.2) to an upper limit of about 93.0
pcs/cm.sup.2 (about 600 pcs/inch.sup.2), and more preferably from a
lower limit of about 38.8 pcs/cm.sup.2 (about 250 pcs/inch.sup.2)
to an upper limit of about 77.5 pcs/cm.sup.2 (about 500
pcs/inch.sup.2).
[0154] On the exhaust gas treating body 10, a catalyst for
purifying exhaust gases may be supported. The catalyst to be
supported is preferably, for example, noble metals such as
platinum, palladium, and rhodium. Particularly preferably among
these is platinum. Other possible catalysts include alkali metals
such as potassium and sodium, and alkaline earth metals such as
barium. These catalysts may be used alone or in combination.
[0155] If these catalysts are supported, PM is more likely to be
removed by combustion, and harmful exhaust gas components can be
purified.
[0156] Next, the metal casing 20 constituting the exhaust gas
purifying apparatus 1 of the embodiment of the present invention is
described.
[0157] FIG. 7 is a perspective view schematically illustrating one
example of the process of accommodating the exhaust gas treating
body having the holding sealing material of the embodiment of the
present invention wound therearound into a metal casing.
[0158] In FIG. 7, the holding sealing material 30 of the embodiment
of the present invention is wound around the exhaust gas treating
body 10 such that the upper layer mat 40 faces the metal casing 20
and the lower layer mat 50 faces the exhaust gas treating body
10.
[0159] The exhaust gas treating body 10 around which the holding
sealing material 30 of the embodiment of the present invention is
wound is press-fitted into the metal casing 20.
[0160] The metal casing 20 is mainly made of a metal such as
stainless steel, and may have a substantially cylindrical shape
with smaller inner diameters at both ends than the inner diameter
at the center portion as illustrated in FIG. 1, or a substantially
cylindrical shape with a constant inner diameter as illustrated in
FIG. 7.
[0161] The inner diameter of the casing 20 (inner diameter of the
portion for accommodating the exhaust gas treating body) is
preferably slightly smaller than the combined length of the
diameter of the ends of the exhaust gas treating body 10 and the
thickness of the holding sealing material 30 in the state of being
wound around the exhaust gas treating body 10.
[0162] Next, one example of the method for manufacturing the
holding sealing material 30 and the exhaust gas purifying apparatus
1 of the embodiment of the present invention is described.
(a) Preparation of Mats
[0163] First, needle-punched mats made of inorganic fibers are
prepared.
[0164] The mat may be prepared by various methods, and one example
is shown below. First, a mixture for spinning which includes raw
materials such as a basic aluminum chloride aqueous solution and a
silica sol is spun by a blowing method to form an inorganic fiber
precursor having an average fiber diameter of from about 3 .mu.m to
about 10 .mu.m. The inorganic fiber precursor is compacted to
manufacture a continuous precursor sheet with a predetermined size.
The continuous precursor sheet is needle-punched and then fired.
These steps complete preparation of the upper layer mat 40 and the
lower layer mat 50.
(b) Adhesion of Film
[0165] Next, the film 60 is adhered to the upper layer mat 40.
[0166] The film 60 is cut into a predetermined shape. The film 60
is adhered to the upper layer mat 40 by winding the film 60 around
the upper layer mat 40 in the direction perpendicular to the
longitudinal direction of the upper mat 40 from the winding start
position 47 to the winding end position 48 on the second main
surface 42 of the upper layer mat 40. Here, the winding start
position 47 and the winding end position 48 are spaced apart from
each other, so that the second main surface 42 of the upper layer
mat 40 is partly exposed.
[0167] The film 60 may be adhered at the same time as covering the
upper layer mat 40 with the film 60 to which an adhesive has been
applied, or may be adhered by thermocompression bonding after
covering the upper layer mat 40 with the film 60.
(c) Lamination
[0168] The upper layer mat 40 is laminated on the lower layer mat
50 such that the first main surface 51 of the lower layer mat 50 is
in contact with the second main surface 42 of the upper layer mat
40. The laminate of the mats is sewn with thread to form the two
fixed parts 32 to fix the mats. The description about the positions
of the fixed parts 32 to be formed is omitted since it has already
been made.
[0169] The laminate of the mats formed through the above steps
serves as the holding sealing material 30 which is one example of
the holding sealing material of the embodiment of the present
invention.
[0170] The step (a) preparation of mats may include applying an
organic binder and/or an inorganic binder to inorganic fibers.
[0171] An organic binder and/or an inorganic binder may be applied
to inorganic fibers by any method and any procedure. For example,
the mats after firing may be immersed in a solution including the
binder(s) to allow the mats to be impregnated with the binder(s),
or the binder(s) may be dropped on the mats by methods such as a
curtain coating method to allow the mats to be impregnated with the
binder(s). After the impregnation, the amount of the binder(s)
adhered to the mats may be adjusted by suction dehydration.
[0172] The following describes one example of the method for
manufacturing the exhaust gas purifying apparatus 1 which is one
example of the exhaust gas purifying apparatus of the embodiment of
the present invention including the holding sealing material
30.
[0173] In the method for manufacturing the exhaust gas purifying
apparatus 1 of the embodiment of the present invention, the exhaust
gas purifying apparatus 1 includes the exhaust gas treating body
10, the metal casing 20 accommodating the exhaust gas treating body
10, and the holding sealing material 30 placed between the exhaust
gas treating body 10 and the metal casing 20. The holding sealing
material 30 is manufactured by the method for manufacturing the
holding sealing material of the embodiment of the present
invention. The method includes winding a laminate of a plurality of
mats (holding sealing material 30) around the exhaust gas treating
body 10 such that the upper layer mat 40 faces the metal casing 20
and the lower layer mat 50 faces the exhaust gas treating body 10;
and press-fitting the exhaust gas treating body 10 with the
laminate of the plurality of mats (holding sealing material 30)
wound therearound into the metal casing 20.
(d) Winding
[0174] The holding sealing material 30 of the embodiment of the
present invention is wound around the exhaust gas treating body
10.
[0175] The holding sealing material 30 is wound onto (along) the
outer periphery of the substantially round pillar shaped exhaust
gas treating body 10 manufactured by known methods such that the
second main surface 52 of the lower layer mat 50 of the holding
sealing material 30 of the embodiment of the present invention is
in contact with the exhaust gas treating body 10. Here, the
projected portion 53a and the recessed portion 54a of the lower
layer mat 50 are fitted together, and the projected portion 43a and
the recessed portion 44a of the upper layer mat 40 are fitted
together.
(e) Press Fitting
[0176] As illustrated in FIG. 7, the exhaust gas treating body 10
with the holding sealing material 30 wound therearound is
press-fitted into the metal casing 20, which is mainly made of a
material such as a metal and has a substantially cylindrical shape
and a predetermined size, by a press-fitting method (stuffing
method).
[0177] The above steps yield the exhaust gas purifying apparatus 1
that is one example of the exhaust gas purifying apparatus of the
embodiment of the present invention.
[0178] In addition, the holding sealing material of the embodiment
of the present invention and the exhaust gas purifying apparatus of
the embodiment of the present invention may have the following
structure.
[0179] Although the above description about the holding sealing
material of the embodiment of the present invention has been made
assuming that the holding sealing material is a laminate of two
mats, the holding sealing material of the embodiment of the present
invention may be a laminate of at least two mats.
[0180] In such a case, the mat with the shortest longitudinal
length among the mats is in contact with the exhaust gas treating
body, and the mat with the longest longitudinal length among the
mats is in contact with the metal casing.
[0181] Although the above description about the holding sealing
material of the embodiment of the present invention has been made
assuming that the mats of the holding sealing material are fixed at
two fixed parts, the mats may be fixed at one fixed part or three
or more fixed parts.
[0182] Although the above description about the holding sealing
material of the embodiment of the present invention has been made
assuming that the mats of the holding sealing material are fixed by
fixed parts, the mats may be bound by at least one band with no
fixing strength. In a holding sealing material with the above
structure, the mats are not fixed to each other. Thus, the mats may
be moved in the longitudinal direction when the holding sealing
material is wound around the exhaust gas treating body. Therefore,
even if the mats are dislocated relative to each other, the
relative position between the mats may be finely adjusted while the
holding sealing material is being wound around the exhaust gas
treating body. As a result, the part where both ends of the holding
sealing material meet is less likely to have a gap.
[0183] The band is preferably made of paper or resin. Paper or
resin may be suitably used as the band with no fixing strength
between the surfaces of the mats and the band.
[0184] Although the above description about the exhaust gas
purifying apparatus of the embodiment of the present invention has
been made assuming that the exhaust gas treating body is an
integrated exhaust gas treating body, the exhaust gas treating body
constituting the exhaust gas purifying apparatus of the embodiment
of the present invention may be an aggregated exhaust gas treating
body formed by binding a plurality of units with adhesive layers
therebetween.
[0185] The exhaust gas treating body constituting the exhaust gas
purifying apparatus of the embodiment of the present invention may
have any shape other than the round pillar shape, such as a
cylindroid shape or a rectangular pillar shape.
[0186] Although the above descriptions have been made assuming that
the exhaust gas treating body is a filter in which either one end
of each cell is sealed, neither end of each cell may be sealed in
the exhaust gas treating body constituting the exhaust gas
purifying apparatus of the embodiment of the present invention.
Such an exhaust gas treating body is suitable as a catalyst
carrier.
[0187] The effects of the holding sealing material, the method for
manufacturing the holding sealing material, the exhaust gas
purifying apparatus, and the method for manufacturing the exhaust
gas purifying apparatus of the embodiment of the present invention
are listed below.
[0188] (1) The holding sealing material of the embodiment of the
present invention includes a laminate of a plurality of mats each
including inorganic fibers and having a rectangle shape in a plan
view, the mats arranged in the order of longitudinal length from
the shortest to the longest. Accordingly, when the holding sealing
material of the embodiment of the present invention is wound around
the exhaust gas treating body, a gap attributed to the different
inner and outer peripheries is hardly generated in the portion
where the ends of the holding sealing material meet. The exhaust
gas purifying apparatus including the holding sealing material of
the embodiment of the present invention therefore has sufficient
sealability for preventing exhaust gas leakage.
[0189] (2) The holding sealing material of the embodiment of the
present invention includes a film adhered to a first main surface
and longitudinal side surfaces of the mat with the longest
longitudinal length among the mats of the laminate, the first main
surface being on the side opposite to a second main surface which
is in contact with the next longest mat.
[0190] The surface of the mat is the part from which inorganic
fibers are scattered. In particular, the mat constituting the
outermost layer of the laminate has the largest radius of
curvature, and thus receives the largest tensile stress when the
holding sealing material is wound around the exhaust gas treating
body. The tensile stress causes the inorganic fibers to be easily
torn. As a result, a defect such as a rip is generated in the
surface of the mat, and thus the inorganic fibers are likely to be
scattered.
[0191] However, if a film is adhered to the mat as in the case of
the holding sealing material of the embodiment of the present
invention, such scattering of inorganic fibers can be reduced.
[0192] (3) In the holding sealing material of the embodiment of the
present invention, the film is adhered also to the longitudinal
side surfaces of the mat with the longest longitudinal length.
[0193] When the exhaust gas treating body with the holding sealing
material wound therearound is press-fitted into a metal casing, the
holding sealing material is compacted in the thickness direction.
The holding sealing material is therefore likely to discharge air
from the longitudinal side surfaces. The discharging air leads to
scattering of inorganic fibers. If the holding sealing material
includes a film adhered to the longitudinal side surfaces of the
mat having the longest longitudinal length as in the case of the
holding sealing material of the embodiment of the present
invention, the structure reduces scattering of inorganic fibers
from the parts to which a film is adhered. Accordingly, scattering
of inorganic fibers can be reduced in dealing with the holding
sealing material of the embodiment of the present invention.
[0194] (4) In the holding sealing material of the embodiment of the
present invention, the film is adhered to also the second main
surface of the mat with the longest longitudinal length, so that
the second main surface is partly exposed. The exposed part allows
the mat with the longest longitudinal length to come into direct
contact with the next longest mat. That is, at this part, the
inorganic fibers contained in the mats are in direct contact and
are thus entangled, whereby the contact between the mats increases.
Furthermore, since the inorganic fibers are rubbed against each
other, the mat with the longest longitudinal length and the mat in
contact with the longest mat are not likely to be dislocated
relative to each other when the exhaust gas treating body around
which the holding sealing material of the embodiment of the present
invention is wound is press-fitted into the metal casing.
Therefore, protrusion of the mat from the end of the metal casing
can be prevented.
EXAMPLES
[0195] Hereinafter, the embodiment of the present invention is more
specifically described by way of examples which, however, do not
intended to limit the scope of the present invention.
Example 1
(a) Preparation of Mats
[0196] (a-1) Spinning
[0197] A silica sol was added to an aqueous basic aluminum chloride
solution adjusted to have an Al content of 70 g/L and an atomic
ratio of Al:Cl=1:1.8 such that the composition ratio (by weight) of
the inorganic fibers after firing would be
Al.sub.2O.sub.3:SiO.sub.2=72:28. To the mixture was added a proper
amount of an organic polymer (polyvinyl alcohol), and thereby a
mixed solution was prepared.
[0198] The obtained mixed solution was concentrated to give a
mixture for spinning. The mixture for spinning was spun by blowing
to manufacture an inorganic fiber precursor having an average fiber
length of 100 mm and an average fiber diameter of 5.1 .mu.m.
(a-2) Compaction
[0199] The inorganic fiber precursor obtained in the above step
(a-1) was compacted to manufacture a continuous precursor
sheet.
(a-3) Needle Punching
[0200] The sheet obtained in the above step (a-2) was continuously
needle-punched under the following conditions, so that a
needle-punched body was manufactured.
[0201] First, a needle board having needles attached thereto at a
density of 21 pcs/cm.sup.2 was prepared. Next, the needle board was
set above one of the surfaces of the sheet, and needle punching was
carried out by allowing the needle board to descend and ascend once
along the thickness direction of the sheet so that a needle-punched
body was manufactured. On this occasion, each needle was made to
penetrate the sheet until a barb formed on the tip of the needle
had completely protruded from the surface on the opposite side of
the sheet.
(a-4) Firing
[0202] The needle-punched body obtained in the above step (a-3) was
continuously fired at a maximum temperature of 1250.degree. C., so
that a fired sheet formed from inorganic fibers including alumina
and silica was manufactured. The average fiber diameter of the
inorganic fibers was 5.1 .mu.m, and the minimum inorganic fiber
diameter was 3.2 .mu.m. The sheet formed from alumina fibers
obtained thereby had a bulk density of 0.15 g/cm.sup.3 and a basis
weight of 1400 g/m.sup.2.
(a-5) Cutting
[0203] The fired sheet obtained in the above step (a-4) was cut
into a cut-off sheet.
(a-6) Impregnation
[0204] The cut-off sheet obtained in the above step (a-5) was
flow-coated with an organic binder solution (acrylic latex)
containing an acrylic resin serving as an organic binder, so that
the cut-off sheet was impregnated with the organic binder. Thereby,
an impregnated sheet was manufactured.
(a-7) Drying
[0205] An excessive organic binder solution was removed by suction
from the impregnated sheet obtained in the above step (a-6), and
the resulting product was dried under pressure, so that a
needle-punched mat having a thickness of 6.8 mm was
manufactured.
(a-8) Cutting
[0206] The mat obtained in (a-7) was cut into the upper layer mat
40 that has a size in a plan view of 1089 mm (full
length).times.371 mm (width) with the projected portion 43a of 24.5
mm (full length).times.100 mm (width) at one end and the recessed
portion 44a to fit the projected portion 43a at the other end.
Similarly, the mat obtained in (a-7) was cut into the lower layer
mat 50 that has a size in a plan view of 1023 mm (full
length).times.371 mm (width).
(b) Film Adhesion
[0207] A film with a polyester pressure-sensitive adhesive
(thickness: 40 .mu.m; KATO SEIKO Co., Ltd.) was cut into a
substantial rectangle with a size of 1050 mm (full
length).times.422 mm (width).
[0208] The film was adhered to the upper layer mat 40 by
continuously winding the film around the upper layer mat 40 from
the winding start position 47 to the winding end position 48 on the
second main surface 42 of the upper layer mat 40, along the second
main surface 42, the first side surface 45, the first main surface
41, the second side surface 46, and the second main surface 42 of
the upper layer mat 40. The winding start position 47 was arranged
at 25 mm from the first side surface 45 toward the second side
surface 46 of the upper layer mat 40, and the winding end position
48 was arranged at 25 mm from the second side surface 46 toward the
first side surface 45 of the upper layer mat 40.
(c) Lamination
[0209] The upper layer mat 40 was laminated on the lower layer mat
50 such that the first main surface 51 of the lower layer mat 50
was in contact with the second main surface 42 of the upper layer
mat 40.
[0210] Then, two fixed parts were formed by sewing with thread to
fix the upper layer mat 40 and the lower layer mat 50.
[0211] The two fixed parts were formed in a manner to each exist
along the direction perpendicular to the longitudinal direction of
the mats of the laminate and to have an interval of 70 mm
therebetween.
[0212] The thus manufactured holding sealing material served as the
holding sealing material 30 of Example 1. The holding sealing
material 30 of Example 1 has such a cross section as illustrated in
FIG. 4 when cut along a line perpendicular to the longitudinal
direction.
(d) Winding
[0213] (d-1) Manufacture of Molded Body of Exhaust Gas Treating
Body
[0214] Coarse particles of silicon carbide with an average particle
diameter of 22 .mu.m (52.8% by weight) and fine particles of
silicon carbide with an average particle diameter of 0.5 .mu.m
(22.6% by weight) were mixed. The resulting mixture was kneaded
together with an acrylic resin (2.1% by weight), an organic binder
(methyl cellulose, 4.6% by weight), a lubricant (UNILUB from NOF
Corp., 2.8% by weight), glycerol (1.3% by weight), and water (13.8%
by weight) to give a wet mixture. The wet mixture was extrusion
molded, so that a molded body of the exhaust gas treating body 10
illustrated in FIG. 6 was manufactured.
(d-2) Drying
[0215] The molded body of the exhaust gas treating body 10 obtained
in the above step (d-1) was dried by a microwave dryer, whereby a
dried body of the exhaust gas treating body 10 was obtained.
(d-3) Degreasing
[0216] The dried body of the exhaust gas treating body 10 obtained
in the above step (d-2) was degreased at 400.degree. C. to
manufacture a degreased body of the exhaust gas treating body
10.
(d-4) Firing
[0217] The degreased body of the exhaust gas treating body 10
obtained in the above step (d-3) was fired at 2200.degree. C. for
three hours in an argon atmosphere under an ordinary pressure, and
thereby a silicon carbide fired body of the exhaust gas treating
body 10 having a porosity of 45%, an average pore diameter of 15
.mu.m, the number of cells (cell density) of 300 pcs/inch.sup.2,
and a cell wall thickness of 0.25 mm (10 mil) was manufactured.
(d-5) Catalyst Supporting
[0218] The silicon carbide fired body of the exhaust gas treating
body 10 obtained in the above step (d-4) was immersed in a nitric
acid platinum solution, was taken out from the nitric acid platinum
solution, and was allowed to stand at 600.degree. C. for one hour.
Thereby, a platinum catalyst was supported on the cell walls 12 of
the silicon carbide fired body of the exhaust gas treating body
10.
[0219] The thus manufactured silicon carbide fired body was used as
the exhaust gas treating body 10 around which the holding sealing
material 30 of the present example would be wound. The exhaust gas
treating body 10 has a substantially round pillar shape with a
length of 350 mm and an outer diameter of 326 mm.
(d-6) Winding of Holding Sealing Material
[0220] The holding sealing material 30 of the embodiment of the
present invention was wound around the exhaust gas treating body 10
obtained through the above step (d-5). Here, the winding of the
holding sealing material 30 was carried out such that the second
main surface 52 of the lower layer mat 50 of the holding sealing
material 30 of this example was in contact with the exhaust gas
treating body 10. The projected portion 53a and the recessed
portion 54a of the lower layer mat 50 were fitted together, and the
projected portion 43a and the recessed portion 44a of the upper
layer mat 40 were fitted together.
(e) Press-Fitting
[0221] The exhaust gas treating body 10 with the holding sealing
material 30 wound therearound was press-fitted into the metal
casing 20 by press-fitting (stuffing). The gap bulk density (GBD)
of the holding sealing material 30 was set to 0.4 g/cm.sup.3.
[0222] The thus manufactured exhaust gas purifying apparatus served
as the exhaust gas purifying apparatus of Example 1.
COMPARATIVE EXAMPLES
[0223] FIGS. 8A to 8C are each a schematic cross-sectional view
taken in the direction perpendicular to the longitudinal direction
of the holding sealing material of a comparative example of the
embodiment of the present invention.
Comparative Example 1
[0224] The exhaust gas purifying apparatus of Comparative Example 1
was manufactured in the same manner as in Example 1 except that the
step (b) film adhesion in Example 1 was changed as in the following
to allow the resulting holding sealing material to have such a
cross section as illustrated in FIG. 8A when cut along a line
perpendicular to the longitudinal direction.
(b) Film Adhesion
[0225] A film with a polyester adhesive was cut into a substantial
rectangle with a size of 1050 mm (full length).times.780 mm
(width).
[0226] The film was adhered to the upper layer mat 40 by
continuously winding the film around the upper layer mat 40 in a
manner to cover all of the second main surface 42, the first side
surface 45, the first main surface 41, and the second side surface
46 of the upper layer mat 40.
[0227] In the holding sealing material of Comparative Example 1,
the upper layer mat 40 and the lower layer mat 50 were completely
separated by the film 60.
Comparative Example 2
[0228] The exhaust gas purifying apparatus of Comparative Example 2
was manufactured in the same manner as in Example 1 except that the
order and procedure of (b) film adhesion and (c) lamination in
Example 1 were changed as in the following, to allow the holding
sealing material to have such a cross section as illustrated in
FIG. 8B when cut along a line perpendicular to the longitudinal
direction.
(b) Lamination
[0229] The upper layer mat 40 was laminated on the lower layer mat
50 such that the first main surface 51 of the lower layer mat 50
was in contact with the second main surface 42 of the upper layer
mat 40.
(c) Film Adhesion
[0230] A film with a polyester adhesive was cut into a substantial
rectangle with a size of 1000 mm (full length).times.780 mm
(width).
[0231] The film was adhered to the upper layer mat 40 and the lower
layer mat 50 by continuously winding the film around the upper and
lower layer mats in a manner to cover all of the first main surface
41, first side surface 45, and the second side surface 46 of the
upper layer mat 40, and the first side surface 55, the second main
surface 52, and the second side surface 56 of the lower layer mat
50.
[0232] Then, two fixed parts were formed by sewing with thread to
fix the upper layer mat 40 and the lower layer mat 50.
[0233] The two fixed parts were formed in a manner to each exist
along the direction perpendicular to the longitudinal direction of
the mats of the laminate and to have an interval of 70 mm
therebetween.
[0234] When the holding sealing material of the Comparative Example
2 is wound around the exhaust gas treating body, the exhaust gas
treating body and the lower layer mat 50 are completely separated
by the film 60.
Comparative Example 3
[0235] The exhaust gas purifying apparatus of Comparative Example 3
was manufactured in the same manner as in Example 1 except that the
step (b) film adhesion in Example 1 was changed as in the
following, to allow the resulting holding sealing material to have
such a cross section as illustrated in FIG. 8C when cut along a
line perpendicular to the longitudinal direction.
(b) Film Adhesion
[0236] A sheet of a film with a polyester adhesive was cut into a
substantial rectangle with a size of 1050 mm (full
length).times.780 mm (width).
[0237] The film was adhered to the upper layer mat 40 by
continuously winding the film around the upper layer mat 40 in a
manner to cover all of the second main surface 42, the first side
surface 45, the first main surface 41, and the second side surface
46 of the upper layer mat 40.
[0238] Subsequently, another sheet of the film with a polyester
adhesive was cut into a substantial rectangle with a size of 1000
mm (full length).times.780 mm (width).
[0239] Then, the film was adhered to the lower layer mat 50 by
continuously winding the film around the lower layer mat 50 in a
manner to cover all of the second main surface 52, the first side
surface 55, the first main surface 51, and the second side surface
56 of the lower layer mat 50.
[0240] In the holding sealing material of Comparative Example 3,
the upper layer mat 40 and the lower layer mat 50 are completely
separated by the film 60. Moreover, when the holding sealing
material of Comparative Example 3 is wound around the exhaust gas
treating body, the exhaust gas treating body and the lower layer
mat 50 are completely separated by the film 60.
[0241] The holding sealing materials of Example 1 and Comparative
Examples were each wound around the exhaust gas treating body, and
the exhaust gas treating body was press-fitted into a metal casing.
Each holding sealing material was visually observed if it protruded
from the end of the metal casing, and the accommodated state of the
holding sealing material was evaluated based on the following
criteria.
(Evaluation Criteria)
[0242] FIG. 9A is a photograph showing the state where the exhaust
gas treating body around which the holding sealing material of the
embodiment of the present invention is wound has been normally
press-fitted into the metal casing. FIG. 9B is a photograph showing
the state where when the exhaust gas treating body around which the
holding sealing material formed by a laminate of mats is wound is
press-fitted, the mats constituting the holding sealing material
are dislocated relative to each other, and the dislocated mats are
protruding from the end of the metal casing.
[0243] A holding sealing material having no protrusion of mats from
the end of the metal casing as illustrated in FIG. 9A was evaluated
as "acceptable". A holding sealing material having a protrusion of
dislocated mats from the end of a metal casing as illustrated in
FIG. 9B was evaluated as "unacceptable".
[0244] The accommodated state of the holding sealing material of
Example 1 was evaluated as "acceptable". The holding sealing
material had no protrusion from the end of the metal casing.
[0245] The accommodated state of the holding sealing material of
Comparative Example 1 was evaluated as "unacceptable". The holding
sealing material had dislocation between the upper layer mat 40 and
the lower layer mat 50 to cause the upper layer mat 40 to protrude
from the end of the metal casing. This is presumably because the
upper layer mat 40 and the lower layer mat 50 were completely
separated by the film 60, which caused insufficient contact between
these mats to result in dislocation between the upper layer mat 40
and the lower layer mat 50.
[0246] The accommodated state of the holding sealing material of
Comparative Example 2 was evaluated as "unacceptable". Although
there is no dislocation between the upper layer mat 40 and the
lower layer mat 50, the upper layer mat 40 and the lower layer mat
50 protruded from the end of the metal casing. This is presumably
because the exhaust gas treating body and the lower layer mat 50
were completely separated by the film 60, which caused insufficient
contact between these to result in dislocation between the exhaust
gas treating body and the lower layer mat 50.
[0247] The accommodated state of the holding sealing material of
Comparative Example 3 was evaluated as "unacceptable". There was
dislocation between the upper layer mat 40 and the lower layer mat
50, and the both mats protruded from the end of the metal casing.
This is presumably because the exhaust gas treating body, the upper
layer mat 40, and the lower layer mat 50 were completely separated
by the film 60, which caused insufficient contact between these to
result in dislocation between the exhaust gas treating body, the
upper layer mat 40, and the lower layer mat 50.
[0248] The holding sealing material of the embodiment of the
present invention essentially features a laminate of a plurality of
mats each containing inorganic fibers and having a rectangle shape
in a plan view, the mats arranged in the order of longitudinal
length from the shortest to the longest; and a film adhered to a
first main surface and longitudinal side surfaces of the mat with
the longest longitudinal length among the mats of the laminate, the
first main surface being on the side opposite to a second main
surface which is in contact with the next longest mat, the film
adhered to the second main surface to allow the second main surface
to be partly exposed.
[0249] The desired effect can be achieved by appropriately
combining the essential features with various structures
specifically described in the Description of Embodiments (e.g., the
shape of the film, the position of the film, the material of the
film, and the method for fixing the laminate of the plurality of
mats).
[0250] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
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