U.S. patent application number 11/200279 was filed with the patent office on 2007-02-15 for methods for substrate retention.
Invention is credited to Ja Hyoung Ku, Michael Paul Lawrukovich, Jarrod Sherwood.
Application Number | 20070033803 11/200279 |
Document ID | / |
Family ID | 37741258 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070033803 |
Kind Code |
A1 |
Lawrukovich; Michael Paul ;
et al. |
February 15, 2007 |
Methods for substrate retention
Abstract
Disclosed herein are methods of substrate retention properties
utilizing compression features. In one embodiment a method for
producing compression features comprises: assembling a mat around a
substrate to form a substrate/mat sub-assembly, disposing the
mat/substrate sub-assembly within a shell to form a retention
assembly, and forming a compression feature on an outer surface of
the retention assembly.
Inventors: |
Lawrukovich; Michael Paul;
(Flushing, MI) ; Sherwood; Jarrod; (Vassar,
MI) ; Ku; Ja Hyoung; (Grand Blanc, MI) |
Correspondence
Address: |
Paul L. Marshall;Delphi Technologies, Inc.
P.O. Box 5052
M/C 480-410-202
Troy
MI
48007
US
|
Family ID: |
37741258 |
Appl. No.: |
11/200279 |
Filed: |
August 9, 2005 |
Current U.S.
Class: |
29/890 ;
29/508 |
Current CPC
Class: |
F01N 3/2853 20130101;
F01N 2450/20 20130101; Y10T 29/49345 20150115; Y10T 29/49913
20150115 |
Class at
Publication: |
029/890 ;
029/508 |
International
Class: |
B21D 39/00 20060101
B21D039/00 |
Claims
1. A method for producing an exhaust treatment device, comprising:
assembling a mat around a substrate to form a substrate/mat
sub-assembly; disposing the mat/substrate sub-assembly within a
shell to form a retention assembly; and, compressing a portion of
the mat by forming a compression feature on an outer surface of the
retention assembly.
2. The method of claim 1, further comprising; measuring a force
exerted on the substrate by the compressed mat; determining if the
measured force is less than a desired force; if the measured force
is less than the desired force, forming subsequent compression
feature(s) on the outer surface until the desired force is exerted
on the substrate.
3. The method of claim 1, further comprising; measuring a process
variable; and, controlling the formation of the compression feature
based on the measurement of the process variable.
4. The method of claim 3, wherein the controlling of the formation
further comprises controlling the depth of the compression
feature.
5. The method of claim 3, wherein the controlling of the formation
further comprises controlling the number of the compression
feature(s).
6. The method of claim 3, wherein the controlling of the formation
further comprises controlling the location of the compression
features.
7. The method of claim 3, wherein the controlling of the formation
further comprises controlling the geometry of the compression
features.
8. A storage medium encoded with a machine readable computer
program code, said code including instructions for causing a
computer to implement a method for producing an exhaust treatment
device, the method comprising: assembling a mat around a substrate
to form a substrate/mat sub-assembly; disposing the mat/substrate
sub-assembly within a shell to form a retention assembly;
compressing a portion of the mat by forming a compression feature
on an outer surface of the retention assembly; measuring a process
variable; and, controlling the formation of the compression feature
based on the measurement of the process variable.
Description
TECHNICAL FIELD
[0001] This disclosure generally relates to methods of substrate
retention within exhaust treatment devices.
BACKGROUND
[0002] Various exhaust treatment devices have demonstrated success
at reducing the gaseous emissions of internal combustion engines.
Devices, such as, particulate filters, NOx adsorbers ("NOx traps"),
fuel reformers, Selective Catalytic Reduction (SCR) substrates, and
the like, can employ a substrate that is capable of converting
emissions such as, carbon monoxide (CO), carbon dioxide (CO.sub.2),
nitrogen oxides (NOx), and the like, into less undesirable species
or compounds.
[0003] Substrates are generally designed to provide a large surface
area which encourages a high percentage of conversion, and can be
produced in many forms, such as, but not limited to, foils,
preforms, fibrous material, monoliths, porous glasses, glass
sponges, foams, pellets, particles, molecular sieves, and the like.
Any materials capable of withstanding elevated operating
temperatures from about 600.degree. Celsius in underfloor
applications to about 1,600.degree. Celsius in manifold mounted or
close-coupled applications can be utilized to manufacture a
substrate. Materials such as, but not limited to, cordierite,
silicon carbides, metal oxides, and the like, have been
successfully employed. Substrates can also employ catalytic metals
on or within the substrate to promote conversion of the gaseous
emissions.
[0004] Generally, substrates are contained within housing
components, comprising an outer "shell" that can be capped on
either end with funnel-shaped "end-cones" or "end-plates", which
can be connected to "snorkels" that allow for easy assembly to
exhaust conduit. Housing components can be fabricated of any
materials capable of withstanding the temperatures, corrosion, and
wear encountered during the operation of the exhaust treatment
device, such as, but not limited to, ferrous metals or ferritic
stainless steels (e.g., martensitic, ferritic, and austenitic
stainless materials, and the like).
[0005] Retention matting (a.k.a. mat, matting) can be utilized as a
packing material concentrically disposed between the shell and the
substrate to support the substrate. Matting can comprise materials
such as, intumescent materials (e.g., a material that comprises
vermiculite component, i.e., a component that expands upon the
application of heat), non-intumescent materials (e.g., ceramic
preforms, ceramic fibers, organic binders, inorganic binders, and
the like), as well as combinations comprising at least one of the
foregoing materials. Non-intumescent materials include materials
such as those sold under the trademarks "NEXTEL" and "INTERAM
1101HT" by the "3M" Company, Minneapolis, Minn., or those sold
under the trademark, "FIBERFRAX" and "CC-MAX" by the Unifrax Co.,
Niagara Falls, N.Y., and the like. Intumescent materials include
materials sold under the trademark "INTERAM" by the "3M" Company,
Minneapolis, Minn., as well as those intumescent materials which
are also sold under the aforementioned "FIBERFRAX" trademark.
[0006] Using matting between the shell and the substrate offers
several benefits. Firstly, matting provides insulation against heat
loss through the metal shell. This is a desirable for the reason
that the substrate operates at an elevated temperature (above about
500.degree. C.) for efficient catalytic conversion. The second
benefit is added impact resistance of the final device. Substrates
can be produced in various designs that can comprise wall
thicknesses of less than 0.005 inches, and even less than 0.003
inches, which can be brittle. Matting offers protection of the
substrate against the occasional impacts encountered during use
(e.g. rocks, accidents, mounting failure, and the like). Thirdly,
the mat offers support of the substrate within the shell as the
shell expands with heat due to the greater degree of thermal
expansion of the metal shell compared to the substrate.
Furthermore, as exhaust pressure increases on the upstream face of
the substrate during use, a pressure gradient is created across the
device that results in an axial force acting on the substrate
towards the low-pressure downstream side. If the substrate is not
retained properly, the device can translate move within the shell
and incur damage. To curtail this possible occurrence, matting can
be compressed between the shell and the substrate to provide
adequate retention forces. However, compressing the mat between the
shell and the substrate creates assembly difficulties that can
result in misalignment and breakage of the catalyst during
insertion, slower production rates, and increased cost of the
components due to tight tolerancing.
[0007] Due to these manufacturing difficulties, device
manufacturers desire novel manufacturing solutions that can provide
adequate retention forces without these detrimental side effects.
Hence, disclosed herein are methods that can provide these
benefits.
BRIEF SUMMARY
[0008] Disclosed herein are methods for improving substrate
retention properties utilizing compression features.
[0009] In one embodiment a method for producing compression
features comprises: disposing a mat around a substrate to form a
substrate/mat sub-assembly, disposing the mat/substrate
sub-assembly within a shell to form a retention assembly, and
forming a compression feature on an outer surface of the retention
assembly.
[0010] In one embodiment, a storage medium encoded with a machine
readable computer program code, said code including instructions
for causing a computer to implement a method for producing an
exhaust treatment device. The method can comprise: assembling a mat
around a substrate to form a substrate/mat sub-assembly, disposing
the mat/substrate sub-assembly within a shell to form a retention
assembly, compressing a portion of the mat by forming a compression
feature on an outer surface of the retention assembly, measuring a
process variable, and controlling the formation of the compression
feature based on the measurement of the process variable.
[0011] The above described and other features are exemplified by
the following figures and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Referring now to the figures, which are exemplary
embodiments, and wherein the like elements are numbered alike.
[0013] FIG. 1 is a cross-sectional illustration of an exemplary
exhaust treatment device 12.
[0014] FIG. 2 is an isometric illustration of an exemplary dimpled
exhaust treatment device 16.
[0015] FIG. 3 is a cross-sectional illustration of an exemplary
ribbed exhaust treatment device 24.
[0016] FIG. 4 is a table illustrating calculated substrate
retention forces.
DETAILED DESCRIPTION
[0017] Disclosed herein are methods for generating substrate
retention forces in assembled exhaust treatment devices. More
specifically, methods are disclosed that are capable of attaining a
desired substrate retention by forming compression features into
the device's shell after the substrate/mat have been assembled
therein. These compression features can create a localized area of
higher density matting, which can exert higher retention forces on
the device's substrate in those areas.
[0018] Disclosed herein are various references to "mat", "matting",
and "retention matting". Despite terminological differences, these
materials are intended to be any materials that can secure a
substrate within an exhaust treatment device, such as, but not
limited to, intumescent materials, non-intumescent materials, and
the like. Furthermore, the term "compression feature" will be
referred to herein and will be interpreted as any feature that can
be imparted into the shell of an exhaust treatment device utilizing
metal forming techniques that compress the matting disposed within
the device about the substrate. In addition, if ranges are
disclosed, these are inclusive and combinable (e.g., ranges of "up
to about 25 wt %, with about 5 wt % to about 20 wt % desired", is
inclusive of the endpoints and all intermediate values of the
ranges of "about 5 wt % to about 25 wt %," etc). Furthermore, the
terms "first," "second," and the like, herein do not denote any
order, quantity, or importance, but rather are used to distinguish
one element from another, and the terms "a" and "an" herein do not
denote a limitation of quantity, but rather denote the presence of
at least one of the referenced item.
[0019] Referring now to FIG. 1, a cross-sectional view of an
exemplary exhaust treatment device, generally designated 12, is
illustrated. Exhaust treatment device 12 comprises substrate 2
disposed within shell 6 with mat 4 disposed therebetween. Shell 6
is connected to cone 8, and end-cone 8 is connected to snorkel 10.
It is also envisioned that shell 6, end-cone 8, and snorkel 10 can
be produced as one component, e.g., using a "spin-form" method,
and/or utilizing multiple components. Furthermore, the shape of
these devices can be of any design, such as, but not limited to
cylinders with circular or non-circular cross-sectional geometries
(e.g., oval, oblong, and the like).
[0020] Exhaust treatment device 12 can be assembled utilizing any
method for producing exhaust treatment devices. More specifically,
in the embodiment illustrated, it is envisioned that mat 4 is
pre-assembled around substrate 2 to form a substrate/mat
sub-assembly, which is then disposed within shell 6 to form a
retention assembly, e.g. utilizing the stuffing assembly
method.
[0021] The stuffing assembly method generally comprises
pre-assembling the mat 4 around the substrate 2 and pushing, or
stuffing, the substrate/mat assembly into a shell 6 through a
stuffing cone. The stuffing cone serves as an assembly tool, which
is basically comprises a hollow cone that can be temporarily
connected to one end of shell 6. At this location, the stuffing
cone can be of similar cross-sectional geometry and of equal or
smaller cross-sectional area than the shell 6. Along the stuffing
cone's length, in a direction away from shell 6, the
cross-sectional geometry can maintain a similar cross-sectional
geometry however gradually taper larger in cross-sectional area. It
is through this larger end that a substrate/mat sub-assembly can be
introduced and advanced. As the substrate/mat sub-assembly is
advanced, the mat 4 around the substrate 2 is concentrically
compressed about the substrate 2 and is eventually compressed to a
point where the substrate/mat sub-assembly can be "stuffed" into
shell 6.
[0022] In an alternative assembly method, known as the "clamshell"
assembly method, shell 6 can comprise two halves, or "clamshells",
that can be assembled around a substrate/mat sub-assembly,
compressing the substrate/mat sub-assembly therein. Once assembled,
the halves can be secured together using any method, e.g.
spot-welding, rolling seam welding, crimping, and the like.
Furthermore, when assembled, the mating halves can be designed to
also form the exhaust treatment device's end-cones 8 and snorkels
10.
[0023] Yet another method of assembly is the tourniquet assembly
method. Again, the tourniquet method comprises pre-assembling a mat
4 around a substrate 2 to form a substrate/mat sub-assembly.
Thereafter a steel sheet can be wrapped around the substrate/mat
assembly and fastened at a seam to comprise the converter's shell.
The end-cones 8 and snorkels 10 can be formed into the steel sheet,
and/or attached as separated components and (e.g. welded, crimped,
and the like) to form the exhaust treatment device.
[0024] Referring now to FIG. 2 an isometric view of an exemplary
dimpled exhaust treatment device is illustrated and generally
designated 16. In this figure, the surface of exhaust treatment
device 12 comprises numerous dimples 14 that have been imparted
into shell 6. The dimples 14 are disposed about shell 6 for the
purpose of providing increased substrate retention. Dimples 14, can
be generally referred to as "compression features" that function to
compress mat 4 between the dimple 14 and the substrate 2, resulting
in a localized area of higher density matting and increased
retention of substrate 2.
[0025] In the exemplary embodiment illustrated in FIG. 2, it is
envisioned that a punching process can be utilized to impart the
multitude of dimples 14. This process can comprise a punch
fabricated to a desired geometry that renders the desired
impression in shell 6. The punching process can generally comprise
actuating a punch to impact shell 6, which contains a mat 4 and a
substrate 2, with sufficient force to impart a dimple 14 or
compression feature. Although the punch is envisioned as having a
configuration that generally leaves a semi-circular impression in
shell 6, the punch can be configured to impart any desired
impression, such as, but not limited to having a conical,
spherical, cylindrical, polygonal, elliptical, or irregular shape,
or the like. In some embodiments, the punching process can pierce
through shell 6 to form tabs, notches, piercings, holes, and the
like.
[0026] Referring now to FIG. 3, an exemplary ribbed exhaust
treatment device, generally designated 24, is illustrated. In the
illustration, the exhaust treatment device of FIG. 3 is depicted
with multiple rib features 18 that have been formed into shell 6.
The rib features 18 can be formed by any method, such as crimping.
The crimping process employed can comprise; first supporting the
device utilizing by any apparatus, such as, but not limited to, a
support structure, frame, support arms, nest, pocket, collets, die,
or the like. Second, a die (not shown) can contact shell 6 and
exert a force in a direction generally designated by force vector
20. Optionally, a simultaneous compression force can be employed to
the device as illustrated by compression force vector 22, which is
applied on cone 8 and/or on snorkel 10, which can result in the
formation of rib feature 18.
[0027] It is apparent however that although punching and crimping
processes have been specifically disclosed, any method of "metal
forming" can be employed to deform the shell 6 in order to form
compression features that result in increased substrate retention,
such as, but not limited to, punching, swaging, stamping, crimping,
peening, forming, and the like. In addition, these metal forming
processes can be repeated in any multiplicity, combination, and/or
configuration desired, and can employ any number of metal forming
operations simultaneously or in subsequent processes to produce the
desired result. Moreover, these processes can also comprise process
controls capable of controlling process variables for beneficial
purposes such as, improved quality, improved efficiency,
repeatability, and the like. For example, to ensure product
quality, one or more process variables can be monitored to ensure
compression features do not inflict damage to substrate 2. These
process variables can be, but are not limited to, force, velocity,
travel, impact depth, punch geometry, inertia, impact angle, or the
like, as well as combinations comprising at least one of the
forgoing and can be measured, monitored, calculated, and/or sensed
utilizing process sensors, switches, meters, data recorders,
transducers, probes, and the like, as well as combinations
comprising at least one of the foregoing, that can be capable of
producing a signal.
[0028] The metal forming methods discussed herein can also employ
additional processing methods or techniques that can assist in
imparting the desired compression features. Processes such as, but
not limited to, annealing, heat-treating, vibration, localized
heating, and the like can be employed. For example, shell 6 can be
annealed prior to a stamping process that forms compression
features, and can optionally undergo a subsequent heat-treating
process after stamping. Another example can employ a heat source
(e.g. flame, and the like) that can be applied directly to a
localized area of shell 6 that can increase the malleability of the
shell 6 prior to and/or during the forming process.
[0029] It is further envisioned that the operating parameters and
processing variables of the metal forming processes described above
can be pre-determined through engineering experiments prior to
manufacturing. For example, the specific pattern, punch force, and
punch depth of a punching operation can be determined prior to
full-scale manufacturing implementation through a series of
experiments that yield a product with the desired substrate
retention.
[0030] Alternatively, or in addition, in-process measurement(s) can
be employed to measure variables that can be employed in the
manufacturing process (e.g., substrate retention forces, mat
density, and the like, as well as combinations comprising at least
one of the foregoing). For example, during assembly, another
process variable (e.g., the retention force of the substrate 2) can
be measured (e.g. utilizing automated methods, such as to test if
the substrate 2 moves (e.g. translates)). If the measured variable
(e.g., force, mat density, etc.) is below a desired value, the
variable can be increased. The variable can be controlled (e.g.,
the force applied to the substrate in a particular area and/or
across the surface of the substrate) in various fashions, such as
by disposing additional compression feature(s) into the shell 6,
(e.g., increasing the number of compression feature(s)), by
increasing the depth of the compression feature(s), by controlling
the compression feature(s)' geometry (e.g., shape, size (depth,
width, etc)). Once the desired value has been attained (e.g.,
retention force, mat density, etc.), process of disposing the
compression feature(s) into the surface of the substrate can be
ceased. It is noted that the compression feature(s) can comprises a
variety of geometries, sizes, and be disposed in various locations
to attain a desired retention force on the substrate in the
particular area. This exemplary method is intended to be
non-limiting and recognized as one of many methods that can be
employed to measure processing variables and operating parameters
during a manufacturing process.
[0031] These methods can be embodied in the form of computer or
controller implemented processes and apparatuses for practicing
those processes. It can also be embodied in the form of computer
program code containing instructions embodied in tangible media,
such as floppy diskettes, CD-ROMs, hard drives, or any other
computer-readable storage medium, wherein, when the computer
program code is loaded into and executed by a computer or
controller, the computer becomes an apparatus for practicing the
method. The method may also be embodied in the form of computer
program code or signal, for example, whether stored in a storage
medium, loaded into and/or executed by a computer or controller, or
transmitted over some transmission medium, such as over electrical
wiring or cabling, through fiber optics, or via electromagnetic
radiation, wherein, when the computer program code is loaded into
and executed by a computer, the computer becomes an apparatus for
practicing the method. When implemented on a general-purpose
microprocessor, the computer program code segments configure the
microprocessor to create specific logic circuits.
[0032] Referring now to FIG. 4, a table is illustrated which
reports calculated results from experiments conducted to evaluate
the total increase in substrate retention forces. The materials
utilized in the experiments were as follows: 1) The matting was
intumescent matting with a density of 6,200 grams per square meter
(g/m.sup.2); 2) The catalytic brick employed measured four-inches
by six-inches (4''.times.6''); and 3) Dimples were modeled as the
compression features on a shell 6 surface disposed in rows aligned
with the axis of the cylinder, totaling 2,070 dimples at 4
millimeters (mm) in diameter each.
[0033] Three sets of calculations were figured to calculate the
resulting catalyst retention forces by both the contribution of the
dimples and of the non-dimpled compressed mat; the first of
calculations was without dimples to determine a baseline catalyst
retention force, the second set of calculations incorporated
dimples at a 1 mm dimple depth, and the third set of calculations
increased the dimple depth to 2 mm. For these three calculation
sets, the non-dimpled and dimpled surface areas are presented, and
the non-dimpled and dimpled retention forces are also
presented.
[0034] In the first calculation (no dimples, dimple depth equals
zero (0) millimeters, mm), the only retention force generated is by
the non-dimpled surface area, which totals 9.40 Newtons (N). In the
second calculation, dimples are imparted into the model at a depth
equal to 1 mm, which results in a non-dimpled area retention force
of 4.79 N and a dimpled area retention force of 11.04 N. Therefore,
incorporating dimples with a 1 mm depth increased the total
retention force to 15.83 N, which corresponds to a 68.4% increase
in retention force, compared to the sample without dimples.
Furthermore, it is calculated that in this experiment that dimples
provides enough additional retention force so that the mat density
can be decreased by 9.50%. More specifically, if the dimpled device
was configured to provide the same retention force as the
non-dimpled device, the mat density can be reduced from 6,200
g/m.sup.2 to 5,609 g/m.sup.2 to generate an equivalent retention
force, hence a 9.50% decrease in mat density.
[0035] The third set of calculations dimples are imparted into the
model at a depth of 2 mm. The retention force generated by the
non-dimpled area of this sample is 4.79 N and the force generated
by the dimpled area is 23.20 N, resulting in a total force of 27.99
N. Therefore, the additional force generated by the dimples results
in a 198% increase in retention force compared to a non-dimpled
sample. This increase in retention force corresponds to a 23.0%
reduction in mat density to generate comparable retention force as
a non-dimpled device (from 6,200 g/m.sup.2 to 4,774 g/m.sup.2).
[0036] As can be seen in the experiment presented, compression
features can increase retention forces and decrease manufacturing
costs through the decrease of mat density.
[0037] In summary, disclosed herein are methods for substrate
retention utilizing compression features that can be imparted in
the shell 6 of an exhaust treatment device after a substrate 2 and
a mat 4 have been disposed therein. The methods disclosed have
demonstrated the capability of improving substrate retention and
decreasing manufacturing costs through the reduction of matting
density. This method also offers several additional benefits, such
as; increased ease of assembly, decreased occurrence of
misalignment/substrate damage, and lower materials cost due to the
potential of wider tolerancing (e.g. shell, catalyst) and decreased
mat density. Combined, these benefits can result in higher
production efficiency and cost-competitiveness for the
manufacturer.
[0038] While the invention has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
* * * * *