U.S. patent application number 11/638945 was filed with the patent office on 2008-06-19 for binder for preforms in silencers.
Invention is credited to Norman T. Huff.
Application Number | 20080142295 11/638945 |
Document ID | / |
Family ID | 39256570 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080142295 |
Kind Code |
A1 |
Huff; Norman T. |
June 19, 2008 |
Binder for preforms in silencers
Abstract
In a method of forming a silencer preform from fibers of a
fiberizable material, the fibers are fed into a mold, and a low
temperature cure binder is applied to the fibers. The binder is
cured at a low temperature to bond together the fibers, thereby
forming a preform having generally the shape of the mold. The
preform is removed from the mold. The preform is structured for
insertion into a silencer. A silencer preform includes fibers of a
fiberizable material and a low temperature cure binder bonding
together the fibers.
Inventors: |
Huff; Norman T.; (Brighton,
MI) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
39256570 |
Appl. No.: |
11/638945 |
Filed: |
December 14, 2006 |
Current U.S.
Class: |
181/256 ;
264/319 |
Current CPC
Class: |
D04H 1/64 20130101; B29K
2995/0002 20130101; F01N 1/24 20130101; B29B 11/16 20130101; D04H
1/74 20130101 |
Class at
Publication: |
181/256 ;
264/319 |
International
Class: |
F01N 1/24 20060101
F01N001/24 |
Claims
1. A method of forming a silencer preform from fibers of a
fiberizable material comprising the steps of: feeding the fibers
into a mold; applying a low temperature cure binder to the fibers
before or after the fibers are fed into the mold; curing the binder
at a low temperature to bond together the fibers thereby forming
the preform having generally the shape of the mold; and removing
the preform from the mold, the preform being structured for
insertion into a silencer.
2. The method of claim 1 wherein the curing is done without
applying heat to the binder.
3. The method of claim 1 wherein the curing is completed in a time
of not greater than about 20 minutes.
4. The method of claim 1 wherein the binder is cured at a
temperature not greater than about 35.degree. C.
5. The method of claim 1 wherein the binder is applied in an amount
within a range of from about 1% to about 20% by weight of the final
preform.
6. The method of claim 1 wherein the binder is substantially
nontoxic, such that when the preform is heated to a temperature of
250.degree. C., the binder emits not greater than the OSHA
permissible exposure limits of toxic gases.
7. The method of claim 1 wherein the binder comprises a resin and a
curing promoter.
8. The method of claim 7 wherein the curing promoter is a
liquid.
9. The method of claim 7 wherein the resin comprises an alkaline
modified phenolic resin.
10. The method of claim 7 wherein the resin and the curing promoter
are applied separately to the fibers.
11. The method of claim 1 wherein at least a portion of the binder
is applied to the fibers using pressurized application
equipment.
12. The method of claim 1 comprising an additional step of adding a
viscosity modifier to at least a portion of the binder before
applying the portion to the fibers.
13. The method of claim 1 wherein the mold is perforated.
14. The method of claim 1 wherein the mold is made partially or
entirely of elastomeric material.
15. The method of claim 1 comprising an additional step of applying
a release agent to the mold prior to feeding the fibers into the
mold.
16. The method of claim 1 wherein the fiberizable material
comprises glass.
17. The method of claim 1 wherein the fibers are texturized.
18. The method of claim 1 wherein the silencer is a component of an
automotive exhaust system.
19. A method of forming an automotive exhaust preform from fibers
of a fiberizable material comprising the steps of: feeding the
fibers into a mold; applying a low temperature cure binder to the
fibers before or after the fibers are fed into the mold; curing the
binder at a temperature not greater than about 50.degree. C. and
for a time of not greater than about 20 minutes, and without
applying heat to the binder, to bond together the fibers thereby
forming the preform having generally the shape of the mold; and
removing the preform from the mold, the preform being structured
for insertion into an automotive exhaust component.
20. A silencer preform comprising: fibers of a fiberizable
material; and a low temperature cure binder bonding together the
fibers to form the preform; the preform being structured for
insertion into a silencer.
21. The preform of claim 20 wherein the automotive exhaust
component is a muffler.
Description
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
[0001] This invention relates in general to fiber preforms and in
particular to preforms for use in silencers such as mufflers or
other automotive exhaust components.
BACKGROUND OF THE INVENTION
[0002] It is common to include sound absorbing material in
automotive exhaust components to dampen or attenuate the acoustic
energy contained in engine exhaust gases as they pass from the
engine through the exhaust system to the atmosphere. Frequently
glass fiber preforms are used as the sound absorbing material.
[0003] Preforms for automotive exhaust components are often made by
texturizing a continuous strand of glass fibers (separating the
strand into individual filaments), feeding the fibers into a mold,
and applying a binder to the fibers as they are texturized or after
they are in the mold. The binder is cured at an elevated
temperature to bond the fibers together, thereby forming a more or
less rigid preform having the shape of the mold. The temperature of
the binder and preform is typically raised to the curing
temperature by blowing hot air into the fibers or placing the
preform with uncured binder into an oven. The heating process can
require significant capital investment as well as significant
amounts of energy, and it can increase the cycle time required for
making the preform.
[0004] German Patent Application No. 06.1092.4.wz discloses a fiber
preform for use in an automotive exhaust component comprising glass
fibers bonded together by a phenolic resin binder. Carbon dioxide
is applied to the binder during the curing process to allow curing
with minimal heating.
[0005] Japanese Patent Publication No. 06-143272 discloses a fiber
preform production method. Chopped glass fibers, a polyester resin
and a curing agent are sprayed together onto a mold. The resin is
then cured at room temperature.
[0006] U.S. Pat. No. 3,927,139 discloses a method of fabrication of
resin bonded fiber reinforced articles by a spray-up technique. The
articles are formed by spraying a catalyst-liquid resin mixture
onto chopped glass fibers. The resin is rapidly cured at room
temperature.
[0007] U.S. Pat. No. 6,426,121 discloses a dual cross-linkable
polymer binder suitable for use in preparing products from a
non-woven web material. The binder is curable at room
temperature.
[0008] U.S. Pat. No. 5,766,541 discloses a method of making a fiber
preform for use in an automotive muffler by feeding glass fiber
strands and a binder into a perforated mold, and blowing heated air
through the mold to cure the binder.
SUMMARY OF THE INVENTION
[0009] The invention relates to a method of forming a silencer
preform from fibers of a fiberizable material. The fibers are fed
into a mold. A low temperature cure binder is applied to the
fibers. The binder is cured at a low temperature to bond the fibers
together, thereby forming a preform having generally the shape of
the mold. The preform is removed from the mold. The preform is
structured for insertion into a silencer.
[0010] The invention also relates to a silencer preform. The
preform comprises fibers of a fiberizable material, and a low
temperature cure binder bonding the fibers together. The preform is
structured for insertion into a silencer.
[0011] Various additional aspects of the invention will become
apparent from the drawings and the detailed description and
preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view of a preform that can be made
according to the invention.
[0013] FIG. 2 is a perspective view of a perforated mold that can
be used to make the preform.
[0014] FIG. 3 is a perspective view of the preform inserted into
the shell of an automotive muffler.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
[0015] In contrast to known preforms for use in silencers, the
preforms of the invention are made with a binder that can be cured
at a low temperature in a relatively brief time. This can
significantly reduce capital and energy costs and the cycle time
required to make the preforms.
[0016] The preforms can be used to make any type of silencer. As is
well known, silencers are components or devices which function to
dampen or attenuate acoustic energy (sound). They often include an
outer shell or housing and a preform which fits inside the
shell/housing. The silencers are often used as part of a larger
system or apparatus. Some systems or apparatuses that may include
silencers are automotive exhaust systems, diesel and gas engines,
compressors, high pressure gas release systems, blowers, vacuum
pumps, vents/blowoffs, and gas turbines.
[0017] By "low temperature cure binder", as used herein, is meant a
binder that can be substantially completely cured (hardened to form
a stable material) at or near room temperature. For example, the
curing temperature may be not greater than about 50.degree. C., and
typically within a range of from about 17.degree. C. to about
35.degree. C.
[0018] The binder can be cured in a relatively brief period of
time, such as a time of not greater than about 30 minutes. For
example, the cure time may be not greater than about 20 minutes,
not greater than about 15 minutes, or within a range of from about
1 to about 10 minutes.
[0019] The binder may be curable at the low temperature without
applying to the binder a nonbinder material that does not become
part of the final binder. For example, as discussed below, a binder
comprising a mixture of a resin and a curing promoter is one
embodiment of the invention. However, the binder may be curable at
the low temperature without applying to the binder a gaseous curing
promoter, such as carbon dioxide.
[0020] The curing may be done without applying heat, such as heated
air or electromagnetic radiation, to the binder. However, in some
instances heat or some type of electromagnetic radiation may be
applied to further speed up the curing process.
[0021] Any suitable low temperature cure binder, or a mixture of
different binders, can be used in the invention. The binder may
comprise a single material or multiple materials. For example, the
binder may comprise a low temperature curing resin. In one
embodiment, the binder comprises a resin in combination with a
material that promotes curing of the resin, such as an activator,
catalyst, or setting/hardening agent. The curing promoter may be a
liquid, emulsion, or particulate solid when mixed with the resin,
which becomes part of the final cured binder on the fibers of the
preform. A liquid curing promoter is used in one embodiment. The
resin and the curing promoter may be applied separately to the
fibers to avoid having the resin cure before bonding together the
fibers to form the preform, although they may also be applied
together.
[0022] Any suitable resin, or a mixture of different resins, can be
used in the binder. Some nonlimiting examples of resins that may be
suitable include alkaline modified phenolic resins that may be
combined with ester setting agents, epoxies that may be combined
with amine setting agents, melamines that may be combined with acid
setting agents, polyurethanes, furans, and urea formaldehydes.
[0023] Some particular examples of alkaline modified phenolic
resins are the ALPHASET.RTM. series of resins manufactured by
Hexion Specialty Chemicals, Columbus, Ohio (formerly Borden
Chemical). For example, the ALPHASET 9010, 9020, 9030 and 9040
resins may be suitable for use in the binder. The different resins
of the series differ somewhat in their viscosity, solids content
and other properties. The ALPHASET.RTM. resins derive their
alkalinity primarily from added sodium hydroxide or potassium
hydroxide. The ALPHASET.RTM. resins are disclosed in U.S. Pat. Nos.
4,424,467 and Re. 32,812. Hexion also manufactures the BETASET.RTM.
(alkaline modified phenolic resins) and the SIGMASET.RTM. (phenolic
urethanes) series of resins that may be suitable for use in the
binder.
[0024] The ALPHASET.RTM. resins can be combined with an ester
setting/hardening agent in the binder to promote curing of the
resin. For instance, Hexion manufactures the ALPHACURE.RTM. series
of liquid ester setting/hardening agents, such as ALPHACURE 103,
104 and 105.
[0025] The ratio of the resin to the curing promoter in the binder
will depend on the particular compositions and process conditions.
For instance, different combinations of resin and curing promoter
can produce different cure rates suitable for different methods of
application and molding techniques. In some embodiments, when the
resin is an alkaline phenolic resin and the activator is an ester,
the resin and the ester may be used in a ratio within a range of
from about 2:1 to about 10:1, or from about 3:1 to about 5:1.
[0026] The amount of the binder applied to the fibers will also
depend on the particular compositions and process conditions. The
binder is applied in an amount sufficient for bonding the fibers
together in the finished preform, and to supply sufficient
mechanical integrity to the preform. The preform maintains its
shape during its subsequent use, for example, during its insertion
into a muffler shell in a muffler assembly operation. The binder
may be applied relatively uniformly throughout the fibers or
applied mainly to the surfaces of the preform. In some embodiments,
the binder is applied in an amount within a range of from about 1%
to about 30% by weight of the final preform, from about 1% to about
20%, from about 2% to about 10%, or from about 2% to about 5%.
[0027] The silencer preforms are often manufactured and/or used in
applications where they are exposed to relatively high
temperatures. For the safety of workers and users, the binder may
be substantially nontoxic such that when the preform is heated to a
temperature of 250.degree. C., for example in a muffler installed
on a vehicle, the binder emits not greater than the OSHA
permissible exposure limits of toxic gases.
[0028] Any suitable fiberizable material, or a mixture of different
fiberizable materials, can be used to make the fibers of the
preforms. For example, methods and compositions for making mineral
fibers such as glass fibers or basalt fibers, polymer fibers,
carbon fibers, asphalt fibers, and mixtures of these fibers are
known in the art. The fibers are able to withstand the thermal,
mechanical and chemical conditions present in the sound attenuating
device into which the preform is inserted.
[0029] The fibers can have any suitable form, such as continuous
fibers, fibers cut into lengths of several centimeters or more, or
chopped fibers typically of length less than 4 centimeters and/or
fibers of several centimeters in length such as those produced in a
mineral wool or AF glass wool process. The fibers may be produced
by attenuating fiber forming material in a fiber-forming apparatus
such as a spinner, bushing or orifice plate, although they may also
be made by any other suitable method. The filaments may be coated
with a sizing composition comprising functional agents such as
lubricants, coupling agents and film-forming polymers, during the
fiber production process. Chopped or cut fibers can be made by
cutting strands into discrete length fibers with a chopper or
similar device well known in the art. Fibers made by a wool process
can also be coated with some type of sizing materials and
subsequently coated with the low temperature cure binder for use in
the preform. The fibers used in the preform may be texturized, by
any suitable method, to increase their sound attenuation/damping
properties, although non-texturized fibers may also be used.
[0030] The binder can be applied to the fibers by any suitable
method. It can be applied either before or after the fibers have
been fed into the mold. For example, it can be applied during the
fiber texturizing or chopping process. The binder can be applied in
any suitable manner, such as spraying, brushing, dip coating or
curtain coating. For example, one method is to separately but
simultaneously spray a liquid resin and a liquid setting agent in
small droplet form onto the fibers as or shortly after the fibers
are texturized.
[0031] A binder or a portion of the binder having a relatively high
viscosity may present difficulties during the application of the
binder to the fibers. For instance, a resin having a relatively
high viscosity may be difficult to spray, which may result in the
sprayer producing a narrow stream of the binder instead of a
dispersed mist that can be applied relatively uniformly throughout
the fibers. Thus, in some embodiments of the invention, at least a
portion of the binder is applied to the fibers using pressurized
application equipment such as a pressurized spray system.
[0032] Alternatively, or in addition to using the pressurized
equipment, a viscosity modifier can be added to at least a portion
of the binder to facilitate its application to the fibers. For
instance, a viscosity reducer such as potassium hydroxide or other
known materials can be added to a relatively viscous resin to
reduce its viscosity.
[0033] The binder often tends to adhere to materials as it cures.
If the binder adheres to the mold surface, it may make the preform
difficult to remove from the mold and/or contribute to build-up on
the mold. Thus, in some embodiments of the invention a release
agent is applied to the mold to prevent or decrease these problems.
Any suitable release agent can be used, such as silicones or
Teflon.RTM.-containing materials.
[0034] Any suitable mold and related apparatus can be used in the
invention. In some embodiments, the mold is perforated, especially
when compressed air is used to texturize the fibers before they are
fed into the mold and/or to apply the binder to the fibers. U.S.
Pat. No. 5,766,541, which is incorporated by reference herein,
describes a perforated mold and related apparatus for making fiber
preforms. Another perforated mold is described hereinbelow and
shown in FIG. 2. However, unperforated molds are also suitable in
some embodiments of the invention.
[0035] When the preform is removed from the mold, the preform is
structured for inclusion as part of the silencer. In some
embodiments, the preform is sized and shaped to substantially fill
an interior cavity of a shell or housing of the silencer, such as
the shell of a muffler, while leaving room for any associated
components devices, such as exhaust pipes, baffles, or perforated
tubes that are associated with mufflers. Alternatively, multiple
preforms can be used to fill the interior cavity of the silencer.
The preforms can be sized and shaped so as to fit any portion of a
silencer.
[0036] Referring now to the drawings, FIG. 1 shows a preform 10
that can be made according to the invention. The preform includes
fibers 10a held together by a binder 10b. The preform is sized and
shaped to substantially fill an interior cavity of a muffler shell.
The preform has three holes 12, 14 and 16 extending through it to
allow pipes associated with the muffler to pass through the
preform.
[0037] FIG. 2 shows a mold 18 that can be used to make the preform
10. The mold includes an oblong-shaped solid bottom end 20. Three
cylindrical tubes 22, 24 and 26 are attached to the bottom end of
the mold and extend perpendicularly therefrom. In the embodiment
shown, the tubes are hollow and have perforated cylindrical
surfaces and solid top ends. The tubes of the mold correspond to
the holes of the preform.
[0038] The mold also includes an outer shell 28. In the embodiment
shown, the outer shell comprises perforated first and second shell
halves 28a and 28b. The shell halves are pivotable about a hinge 30
at one end of the shell, for opening and closing the outer shell.
The outer shell includes clamps 32, 33 and 34 at the other end of
the shell for fastening closed the shell halves. The interior of
the closed outer shell defines a cavity having the approximate size
and shape of an interior cavity of a muffler shell.
[0039] The mold further includes an oblong-shaped solid top 36. The
top 36 of the mold has three holes 38, 40 and 42 to allow the top
ends of the tubes 22, 24 and 26 to pass therethrough when the top
is installed on the mold. The top includes flanged bars 44 and 46
on its ends that abut the end of the outer shell to facilitate the
positioning of the top onto the mold. The top 36 may be designed to
fit inside the mold shell 28 so that the sound absorbing material
in the mold can be compressed to a given height determined by tabs
(not shown) on the inside of the mold shell.
[0040] The mold can be made out of a variety of materials since it
does not have to be heated to above near room temperature in order
for the binder to be cured. Making the mold out of material which
would be resistant to the binder sticking to the mold (e.g.
Teflon.RTM.) could make removal of the preform from the mold more
efficient. In addition, portions of the mold (e.g. the tubes) or
the entire mold could be made of an elastomeric material which
would allow the size and shape of the mold to be changed for easy
removal of the preform.
[0041] Owens Corning sells Silentex.RTM. machines which are
typically used to fill mufflers or preform molds or bags with
texturized fiberglass materials. This type of machine uses as input
material a fiberglass strand containing several thousand individual
fibers. The strand passes through a nozzle into which compressed
air is introduced. The compressed air serves to separate the
individual filaments so that they will more efficiently attenuate
acoustic energy. In addition, the compressed air helps to move the
texturized strand out of the nozzle and into whatever type of
container is to be filled. In this invention, the binder could be
supplied to the nozzle so that two streams of liquid could be
introduced into the nozzle after the material is texturized or
could be applied to the texturized material immediately after
exiting the nozzle and applied to the texturized strand before or
as the strand enters the mold. The texturized strand coated with
the binder may be directed into the mold in a manner which ensures
uniform filling of the mold without negatively impacting the
quality of texturization of the strand. One or more dimensions of
the mold may be reduced after the texturized material is introduced
into the mold so that the preform will be of the proper size that
it can easily be installed in a silencer.
[0042] FIG. 3 shows the preform 10 inserted into the shell 48 of an
automotive muffler 50. It is seen that the preform substantially
fills the interior cavity of the muffler shell, although such is
not necessary.
[0043] One skilled in the art will appreciate that the invention is
not limited to the particular methods and compositions described
herein, and that changes can be made without departing from the
scope of the invention, which is defined in the appended
claims.
* * * * *