U.S. patent number 3,921,273 [Application Number 05/512,872] was granted by the patent office on 1975-11-25 for method of filling a casing with heat insulating fibers.
This patent grant is currently assigned to Toyota Jidosha Kabushiki Kaisha. Invention is credited to Katsumi Kondo, Mikio Murachi, Fumiyoshi Noda, Masaru Usui, Yuji Watanabe.
United States Patent |
3,921,273 |
Kondo , et al. |
November 25, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Method of filling a casing with heat insulating fibers
Abstract
Method of filling a casing with heat insulating fibers in which
a fibrous heat insulating mass of fixed size is inserted into a
space to be filled by vacuum-packing the fibrous mass in a
vacuum-resistant bag, which may then be wrapped about an inner
cylinder, introducing the bag into an outer cylinder and, after
breaking the vacuum seal, allowing the fibrous mass to swell and
fill any space within the outer cylinder not occupied by said inner
cylinder, if any.
Inventors: |
Kondo; Katsumi (Toyota,
JA), Noda; Fumiyoshi (Toyota, JA), Murachi;
Mikio (Toyota, JA), Watanabe; Yuji (Toyota,
JA), Usui; Masaru (Toyota, JA) |
Assignee: |
Toyota Jidosha Kabushiki Kaisha
(Toyota, JA)
|
Family
ID: |
14612712 |
Appl.
No.: |
05/512,872 |
Filed: |
October 7, 1974 |
Foreign Application Priority Data
|
|
|
|
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Oct 9, 1973 [JA] |
|
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48-113457 |
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Current U.S.
Class: |
29/890; 29/423;
29/453; 29/890.06; 29/235; 29/451; 29/455.1; 138/149 |
Current CPC
Class: |
B29C
44/185 (20130101); F16L 59/028 (20130101); B29C
44/3496 (20130101); F01N 3/26 (20130101); F16L
59/16 (20130101); B01D 53/944 (20130101); Y10T
29/53657 (20150115); F01N 2310/06 (20130101); Y10T
29/49394 (20150115); Y10T 29/49872 (20150115); Y10T
29/49345 (20150115); Y10T 29/4981 (20150115); Y10T
29/49879 (20150115); Y10T 29/49398 (20150115); Y10T
29/49876 (20150115) |
Current International
Class: |
F16L
59/00 (20060101); F16L 59/16 (20060101); B01D
53/94 (20060101); F01N 3/26 (20060101); F16L
59/02 (20060101); B21D 053/00 (); B21K 029/00 ();
B23P 015/26 () |
Field of
Search: |
;29/450,157R,451,235,423,455,157 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Moon; Charlie T.
Attorney, Agent or Firm: Brisebois & Kruger
Claims
What is claimed is:
1. Method of manufacturing a heat insulator which comprises the
steps of introducing between an outer casing and an inner casing an
insert comprising a mass of fibrous material which has been
compressed by vacuum-packing it in a hermetically sealed bag, and
then unsealing said bag to permit said material to expand within
said casing.
2. Method as claimed in claim 1 which comprises the step of first
wrapping said sealed bag containing said mass of fibrous material
about an inner casing to form the insert introduced into said outer
casing.
3. Method as claimed in claim 1 in which said bag is sealed in such
a way that it may be unsealed by the application of an amount of
heat insufficient to damage said fibrous mass and casing, and
comprising the step of applying said amount of heat to said
insulator after said bag has been introduced into said casing.
4. Method as claimed in claim 1 in which said bag is made of a
material which is destroyed by the application thereto of an amount
of heat insufficient to damage said casing and fibrous mass, and
comprising the step of applying said amount of heat to said
insulator after said bag has been introduced into said casing.
5. Method as claimed in claim 1 in which said fibrous material is
selected from the group consisting of rock wool, silica fiber,
ceramic fiber, and mixtures thereof.
6. Method as claimed in claim 1 in which said bag is made from a
plastic selected from the group consisting of nylon, polyethylene,
polypropylene, and combinations thereof.
7. Method as claimed in claim 1 in which the fibrous mass is caused
to fill the space between inner and outer cylindrical casing
encircling a passage for the gas exhausted from an automotive
engine.
Description
BACKGROUND OF THE INVENTION
Automobile exhaust gas purifiers such as manifold reactors or
catalytic converters should comprise a heat insulator which can
withstand high temperature, because the inside of such a device has
to be kept warm so that its exhaust gas purifying ability may be
improved and the heat released from such a device has to be
prevented from affecting adjacent parts of the automobile.
The so-called ceramic fibers, which are fibrous heat insulators for
high temperature use constitute one of the materials available for
this purpose. Fibers of alumina-silica can withstand a maximum
working temperature of 1200.degree.-1400.degree.C; one of silica
can withstand 1000.degree.C; one of potassium titanate can
withstand about 1000.degree.C; and one of zirconia can withstand
1800.degree.C. Slag wool is also available, but the working
temperature it can withstand is low, i.e., about 600.degree.C.
These fibrous materials have a heat insulating ability two to three
times as high as that of heat resistant, heat insulating brick; a
bulk specific gravity of 0.05-0.25 g/cm.sup.3, which is about 1/8
of that of the heat insulating brick; and are flexible and
vibration-resistant, so as to be quite free from the possibility of
being broken by heat shock. Being less resistant to wind velocity,
however, they usually need a heat-resistant metal plate applied on
the heating surface and are sandwiched between the metal plate and
the outer shell, when they are used in a manifold reactor. When
they are used in a catalytic converter, they fill the space between
the catalyst carrier and the outer shell. In any case, the fibrous
heat insulator has to fill a very narrow space. To do this
efficiently without sacrificing performance, various methods have
been worked out. To give some examples, there are:
1. The method of inserting a bulky heat insulator through the end
of the space between the heat insulating inner cylinder and outer
cylinder;
2. The method of introducing into the outer cylinder an inner
cylinder wrapped with a felt-like heat insulator, or sheathing the
inner cylinder with an outer cylinder split into two parts; and
3. The method of inserting a stainless steel, foil-packed fibrous
heat insulator. There are, however, many drawbacks in these
methods. For example:
1. The efficiency is poor;
2. The fill density becomes uneven; and
3. It is expensive.
SUMMARY OF THE INVENTION
The present invention provides a method of filling a narrow heat
insulating space in an exhaust gas purifier such as a manifold
reactor. According to the present invention, the reactor can be
filled with a fibrous heat insulator with extremely high efficiency
and uniformity, thereby substantially increasing the work
efficiency. Moreover, since the space can be filled to a high
density with the fibrous heat insulator, its heat insulating
capacity can be improved and accordingly the purifying performance
of the exhaust gas purifier can be increased, while the amount of
heat released can be decreased.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the assembly comprising the engine, the manifold
reactor, the exhaust pipe and the muffler.
FIG. 2 is a perspective view of the manifold reactor fitted to the
engine, with part of the reactor wall shown broken away.
FIG. 3 is a longitudinal sectional view taken through the manifold
reactor.
FIG. 4 is a sectional view taken along the line II--II' of FIG.
3.
FIG. 5 is an oblique view of a heat insulator with specified
portions stamped out.
FIG. 6 is an oblique view of the heat insulator of FIG. 5 as
vacuum-packed.
FIG. 7 is a partial sectional view taken through a vacuum-packed
heat insulating inner cylinder attached to a heat insulator.
FIG. 8 is a sectional view of a heat insulating cylinder
accessory.
FIGS. 9-14 are diagrams showing the thickness of a heat insulator
when it is vacuum-packed and when the vacuum seal is broken.
FIG. 15 is a diagram showing the thermal conductivities of ceramic
fiber blankets with various densities.
FIG. 16 is a partially fragmented oblique view of a heat insulated
exhaust pipe.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, which relies on the
compressibility of a fibrous heat insulating material, the fibrous
heat insulating material is placed in a heat-resistant film bag;
the bag is depressurized to compress and reduce the volume of the
fibrous heat insulator; the heat insulating material which has been
thus compressed and reduced in volume is inserted into the space to
be insulated from heat; and then the vacuum seal of said bag is
broken to expose its contents to atmospheric pressure, so that said
insulating material expands to fill said space.
According to the present invention, the same purpose may also be
attained by placing fibrous heat insulating material, which has
been cut to the size of a space to be filled, into a
vacuum-resistant film bag; vacuum-packing the resulting assembly;
inserting it into the space to be filled; and then breaking the
seal of the package. In the case of a manifold reactor or a
catalytic converter having an intricate configuration of inner and
outer cylinders, unlike the case of an ordinary heat insulated pipe
in which a heat insulator is introduced between outer and inner
cylinders having smooth surfaces, it would be advisable to apply a
laminated layer of the fibrous heat insulating material on the
surface of the inner cylinder, insert the whole inner cylinder into
a film bag which is then hermetically sealed for vacuum-packing;
and then break the seal of the vacuum-package after having
introduced it into the outer cylinder.
As understood from the above, the hermetically sealed bag to be
used in the present invention should desirably be flexible and for
this purpose the flexible plastic film should be one that does not
break when vacuum-packed. For instance, nylon, polyethylene,
polypropylene films, etc. may be used singly or as a laminated
sheet. Preferably, the film should vanish when burned.
In addition to the above-mentioned ceramic fiber as a fibrous heat
insulator, anything fibrous with elasticity may be used for the
present invention.
Tables 1-3 give the characteristic values of a few examples of the
fibrous heat insulator. FIGS. 9-14 show the thicknesses of these
materials when they are vacuum-packed under various pressures and
when their hermetic seal is broken. FIG. 15 shows the thermal
conductivities of ceramic fiber blankets with various
densities.
TABLE 1 ______________________________________ Characteristic
values of ceramic fiber blankets
______________________________________ Item Characteristic values
______________________________________ Fiber diameter 2.8.mu.
average Fiber length 100 mm average True specific gravity 2.56
Melting point 1760.degree.C Al.sub.2 O.sub.3 50.1% SiO.sub.2 49.1%
Chemical Fe.sub.2 O.sub.3 0.2% TiO.sub.2 0.2% CaO 0.1% Composition
MgO Trace Na.sub.2 O 0.3%
______________________________________
TABLE 2 ______________________________________ Characteristic value
of rock wool* ______________________________________ Items
Characteristic values ______________________________________ Fiber
diameter 4-6.mu. Density 0.11-0.15 g/cm.sup.3 Particle-content less
than 3% Working temperature -200-800.degree.C range SiO.sub.2
35-45% Chemical Al.sub.2 O.sub.3 10-15% CaO 30-40% Composition MgO
5-7% ______________________________________ *S-fiber produced by
Shin-Nihon Seitetsu Kagaku
TABLE 3 ______________________________________ Characteristic
values of silica fiber* ______________________________________
Items Characteristic values ______________________________________
Fiber diameter 1.3.mu. average Fiber length 20 mm average True
specific 2.52 gravity Melting point 1713.degree.C Chemical
SiO.sub.2 98% Na.sub.2 O 0.3% Composition Others 1.7%
______________________________________ *product of Nihon Glass
Fiber Co.
FIG. 9 illustrates the thickness of a rock wool mass, initially
measuring 20 mm thick, 100 mm wide and 100 mm long, after
vacuum-packing under various vacuum pressures. As seen therefrom,
the thickness of the rock wool is reduced to about 1/3 of its
initial value. The term "vacuum pressure" as used here means the
difference between atmospheric pressure and the pressure attained
after the maximum depressurization. As shown in FIG. 10, when the
hermetic seal is broken, the thickness of the mass is restored at
most to about twice the thickness when vacuum-packed. The
vacuum-resistant film used was a 50.mu. thick polyethylene film
laminated to a 15.mu. thick nylon film. The same film was used in
all other cases.
FIG. 11 illustrates the thicknesses of ceramic fiber blankets (as
listed in Table 1) with various densities measuring 12.5 mm thick,
100 mm wide and 100 mm long, after vacuum-packing under various
vacuum pressures.
FIG. 12 illustrates the thicknesses of those blankets in FIG. 11
after the hermetic seal is broken. As seen from FIG. 11,
vacuum-packing reduces the thickness of the ceramic fiber blanket
to as little as 1/4 of the initial value; when the hermetic seal is
broken, a substantial increase from the vacuum-packed thickness
takes place as indicated in FIG. 12.
FIGS. 13 and 14 respectively show the vacuum-packed thickness and
the vacuum-broken thickness of the ceramic fiber blankets in FIGS.
11 and 12 when they are initially made 25 mm thick.
As described above, the fibrous heat insulator can be compressed to
a fraction of its original thickness by vacuum-packing. When the
vacuum pressure is 1 kg/cm.sup.2, the compressive pressure rises to
a maximum, i.e., 1 kg/cm.sup.2.
A vacuum-packed fibrous heat insulator, when the vacuum has been
broken, swells from several tens to one hundred per cent in the
direction of its thickness. Therefore, when the vacuum of a
vacuum-packed heat insulator that can swell to twice its
vacuum-packed thickness is within a space 1.5 times the thickness
of the insulator, the insulator will swell to fill the space, and
still have an extra capacity to expand. Thus with high density
retained, the heat insulator will have a low thermal conductivity,
an excellent insulating performance and excellent resistance to
vibration, as illustrated in FIG. 15. There is another advantage,
in that even when the dimensions of the inner or the outer cylinder
change due to the temperature variations, the insulator can
correspondingly swell, showing no great change in heat insulating
performance.
Several specific embodiments of the present invention will now be
described.
EXAMPLE 1
In FIGS. 1-4 showing the engine, manifold reactor, exhaust pipe and
muffler reference numeral 1 indicates the engine; 2 indicates the
manifold reactor in which CO and HC among the harmful emissions
from the engine 1 are burned and transformed into harmless CO.sub.2
and water; and 3 indicates the exhaust pipe which carries the
exhaust gas out of the exhaust port of the manifold reactor 2 to
the muffler 4.
In the engine 1, 1e is the combustion chamber of the engine, in
which the gasoline and the air react with each other in an
explosion which generates the exhaust gas. When the exhaust valve
1a opens, the exhaust gas passes out through the exhaust port 1f.
Reference number 1g indicates the valve seat, 1c the water-cooled
jacket for cooling the cylinder head 1b. 1d indicates an air inlet
pipe through which an air pump introduces air to the exhaust port
1f to promote the re-combustion of the exhaust gas expelled through
the exhaust port 1f, and 1h indicates a gasket. A mixture of the
air introduced through the air pipe 1d and the exhaust gas passes
into the cylindrical exhaust gas inlet 5 of the manifold reactor 2
and then enters the cylindrical combustion chamber 6. The exhaust
gas which has been burned again in the combustion chamber 6 passes
through the cylindrical gas outlet 19 into the exhaust pipe 3, and,
with the noise muffled by the muffler 4, passes out of the tail
pipe 4'.
In the above arrangement the gas temperature in the re-combustion
chamber 6 reaches 900.degree.-1000.degree.C. In order to shield the
surrounding parts from this heat, the space between the inner
cylinder 7 and the outer cylinder 8 is filled with fibrous heat
insulators 9, 9'. Reference numeral 10 indicates a cylindrical heat
insulating duct for preventing the material of the heat insulators
9, 9' from dispersing into the exhaust gas. This duct is welded to
the inner cylinder 7 and the outer cylinder 8 at the exhaust gas
inlet and outlet.
The method of filling the heat insulators 9, 9' in this embodiment
will now be described.
A ceramic fiber blanket having the properties indicated in Table 1
(a product of Isolite Industry K.K., trade name "Kao-wool blanket,"
having a density of 0.128 g/cm.sup.2, and a thickness of 12.5 mm)
is cut into a piece of such size that it can be wrapped around the
heat insulating inner cylinder 7. After cutting a hole therein for
the heat insulating duct 9b of the exhaust gas inlet and for the
heat insulating duct 9c of the exhaust gas outlet, a blanket 9a, as
illustrated in FIG. 5 is obtained. This blanket 9a is wrapped
around the inner cylinder 7 which has the side cover 7' of the
inner cylinder and the heat insulating duct 10 welded thereto, and
the end faces 9e, 9e' of the blanket are joined together and
attached by means of a tape or the like. In addition, a blanket
heat insulator 9' of the disk type is prepared with a hole provided
therein for receiving the bolt 16 to support the inner cylinder 7
and this is pressed and fitted against the end cover 7' of the
inner cylinder.
The inner cylinder 7, thus firmly wrapped in a blanket, is placed
in a vacuum-resistant bag (such as the one mentioned above) and
vacuum-packed under a vacuum pressure of 1 kg/cm.sup.2. For this
purpose, a vacuum-packer Model A-450-L produced by Furukawa
Seisakusho is employed; and this machine is also used in the
following examples.
FIG. 7 illustrates the reactor in a vacuum-packed state. In FIG. 7,
reference numeral 20 is a vacuum-resistant bag, 21 is the hermetic
seal, and 21' is the sealed bottom of the bag. As a result of such
a vacuum-sealing, the thickness of the heat insulating layer can be
reduced to 4.9 mm, including the thickness of said vacuum-resistant
bag.
The vacuum-packed product illustrated in FIG. 7 is introduced into
the outer cylinder 8 and heated at 500.degree.C for 30 minutes to
burn away the vacuum-resistant bag. Thus released from vacuum, the
blanket swells and uniformly fills the 8 mm gap between the inner
and outer cylinders 7, 8. Then the heat insulating duct 10 and the
heat insulating outer cylinder 8 are welded together, and the end
cover 8' is welded to the outer cylinder 8, thereby completing the
heat insulating cylinder accessory (FIG. 8). The blanket 9' may be
inserted in a conventional way before the end cover 8' is welded to
the outer cylinder 8.
The heat insulating cylinder accessory constructed in this manner
is inserted into the outer cylinder 11; the end cover 15 and gasket
18 are attached; the support bolt 16 for the inner cylinder 7 is
inserted and the end cover 15 is bolted by the bolt 17 to the outer
cylinder 11.
Thereafter the manifold reactor is completed by providing the ducts
13, 14 (see FIG. 3). This reactor is then bolted to the engine by
means of the bolt 12.
Among the components of the manifold reactor, the inner cylinder 7,
the outer cylinder 8, the ducts 13, 14 and the bolt 16 are made of
stainless steel, JIS-SUS-310S; the bolt 12 is made of stainless
steel JIS-SUS-304; and the outer shell 11 and the end cover 15 are
made of cast iron (FCG-23).
EXAMPLE 2
The same ceramic fiber blanket as in Example 1 is used and by
subjecting it to the same treatment as in Example 1, a blanket 9a
(FIG. 5) to be wrapped around the inner cylinder 7 is prepared.
This blanket 9a is placed in a vacuum-resistant bag 20 (the same as
above) of polyethylene laminated to nylon, and is vacuum-packed.
The vacuum-packed product has its parts corresponding to the heat
insulating ducts 9b, 9c for inlet and outlet of the exhaust gas in
the blanket 9a heat-sealed; and with openings for receiving the
heat insulating ducts stamped out, a vacuum-package as illustrated
in FIG. 6 is obtained.
This vacuum-package is wrapped around the inner cylinder 7,
fastened with a tape or the like and inserted into the outer
cylinder 8, after which it is treated as in Example 1, thereby
making a heat insulating cylinder accessory and completing a
manifold reactor.
In this embodiment the heat insulator 9' to fill the end of the
heat insulating cylinder may be vacuum-packed before insertion just
as in Example 1, or it may be inserted in a conventional way.
In the present example, in which only the blanket is vacuum-packed,
its original thickness of 12.5 mm can be reduced to 4.5 mm,
including the thickness of the bag, which is thinner than in
Example 1.
A heat insulating cylinder accessory prepared as in Examples 1 and
2 was compared in a vibration test with a heat insulating cylinder
accessory prepared by inserting a 7 mm thick ceramic fiber blanket
of the same quality as in Example 1 by a conventional method. The
test conditions were as described below, and after the test, each
accessory was cut open for investigation. The results show that the
products of Examples 1 and 2 were uniformly filled, but the
conventional product had its blanket loosened, bulky and bent
toward the bottom of the accessory.
______________________________________ Test conditions:
______________________________________ Frequency: 90 Hz Vibrational
acceleration: 45 G Amplitude: about 2 mm Test time: 5 hours Test
apparatus: electromagnetic vibration tester Vibrational directions:
normal to the diameter of heat insulating cylinder and up and down
______________________________________
EXAMPLE 3
In this example, a method of filling a heat insulated exhaust pipe
is described, a partially cut away oblique view thereof being shown
in FIG. 16, with a heat insulator. In FIG. 16, reference numeral 22
indicates an outer cylinder made of JIS-STKM-11 steel, 23 an inner
cylinder made of JIS-SUS-304 steel, and 25 a flange made of
JIS-SUS-304 steel, while 26 indicates the bolt hole.
First, a rock wool pad, 0.14 g/cm.sup.2 in density and 20 mm in
thickness (a product of Shin-Nippon Seitetsu Kagaku, see Table 2)
is wrapped around the inner cylinder 23, which has a flange 25
welded thereto at 23a; the butt joint is firmly taped; and the
resulting assembly is inserted into a heat resistant film bag (the
same type as in Example 1). It is then vacuum-packed to a vacuum
pressure of 1 kg/cm.sup.2. Vacuum-packing reduces the thickness of
the wool pad to 6.4 mm.
Next the resulting vacuum-package is introduced into the outer
cylinder 22, and heated at 500.degree.C for 20 minutes to burn away
the vacuum-resistant film bag. Thus released from the vacuum, the
heat insulator 24 fills the space between the inner and outer
cylinders.
The outer diameter of the inner cylinder is 40 mm, the inner
diameter of the outer cylinder is 56 mm, and the thickness of the
heat insulating space between the two cylinders is 8 mm.
EXAMPLE 4
A 25 mm thick rock wool pad of the same quality as in Example 3 is
used as the heat insulator. A layer of this wool is cut into a
piece of specified size, which is inserted into a vacuum-resistant
bag (of the same type as above) and vacuum-packed, to a vacuum
pressure 1 kg/cm.sup.2. Thus vacuum-packed, the thickness,
including that of the bag, can be reduced to 6.5 mm.
Next the resulting vacuum-package is wrapped around the inner
cylinder 23 having the flange 25 welded thereto, the butt joint is
firmly taped, the inner cylinder 23 thus treated is introduced into
the outer cylinder and heated at 500.degree.C for 30 minutes to
burn away the vacuum-resistant bag. Thus released from vacuum, the
space between the two cylinders is filled with the heat insulator,
thereby producing a heat insulated exhaust pipe.
In the conventional practice of wrapping the heat insulator around
the surface of the inner cylinder and simply forcing the inner
cylinder into the outer one, a heat insulator about 4 mm thick at
the most is available for the manufacture of the above-mentioned
heat insulated exhaust pipe. Thus in comparison between the
products of Examples 3, 4 and the conventional product in a
vibration test (the conditions being the same as above), the
conventional product was found to be extremely one-sided, resulting
in a heavy drop in its heat insulating effect, whereas the products
according to the present invention were free from such a
defect.
As described above, the present invention makes the filling of the
heat insulator easy so that the fibrous heat insulator can be
filled to such high density that the filled layer can exhibit
excellent anti-vibration characteristics and heat insulating
properties. Moreover, the present invention eliminates the sanitary
problem of fine particles of the fibrous heat insulator becoming
scattered into the air at the work site, and many other benefits
accrue from the present invention.
* * * * *