Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CATALYTIC CONVERTER AND RESONATOR COMBINATION
BACKGROUND OF THE INVENTION
1~ FIELD OF THE INVENTION
The present invention relates generally to
automobile exhaust emission control, and more
specifically to a device combining a catalytic exhaust
converter and a resonator installed within the exhaust
system for the reduction of exhaust noise. Several
embodiments are disclosed herein, for single and dual
ZO exhaust systems and for single and plural catalytic
converter elements therein.
2. DESCRIPTION OF THE RELATED ART
By the time of the 1950s, it was becoming apparent
that the ever increasing volume of automobile and
truck traffic was generating exhaust emissions which
were adversely affecting the environment. This was
particularly true in urban areas and other areas where
geographic and meteorological conditions combined to
create areas where such emissions do not readily
dissipate. Accordingly, by the late 1960s, various
regulations were being implemented to require
equipment to reduce exhaust emissions output from
automobiles, particularly in California and other
urban areas.
While early emissions control efforts provided some
relief, standards have become increasingly strict in
order to keep pace with the ever increasing volume of
automobile and truck traffic throughout the U. S. A.
With the development of the catalytic converter, which
uses one or more noble metals such as platinum,
rhodium, and/or palladium to produce an oxidizing
and/or reducing catalytic reaction with the exhaust
products and heat generated by the exhaust, a real
breakthrough was achieved in the control of vehicle
emissions. An automobile equipped with ane or more
catalytic converters was capable of meeting most, if
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not all, of the exhaust emissions standards of the
time, and the use of catalytic converters became
commonplace on automobiles and light trucks powered by
spark ignition engines in the U. S. A.
However, long before the recognition of chemical or
particulate automobile exhaust emissions as a hazard,
another type of automobile exhaust emission had been
recognized, i. e., noise or sound. In fact,
legislation in virtually every area of the world
requires motor vehicles to have equipment which
reduces this other emission: Accordingly, mufflers,
resonators and other such sound attenuating devices
have been known for many years, since shortly after
the very earliest development of the internal
combustion engine. These two types of emissions
control devices, i. e., catalytic converters and
mufflers or other sound attenuating devices, have
generally not been combined into a single unit due to
conflicting characteristics and physical requirements.
In the case of exhaust silencing devices, the
maximum desired temperatures for such devices in
operation are generally relatively low in comparison
to the temperatures achieved in catalytic converters.
Mufflers, resonators, and such sound attenuating
devices are generally constructed of mild steel,
perhaps with an aluminized exterior .coating. Very
high temperatures cause the aluminized coating to be
burned off, and cause both the interior and (after
removal of any coating) exterior to be oxidized, to
the point of burn through or rust through, in
relatively short order. While mufflers and other
related devices have been constructed of stainless
steel in order to reduce oxidation problems, these
devices are relatively costly due to the material used
and the difficulty in working with such material, in
comparison to mild steel. Many, if not most,
automobile owners would rather replace a standard
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steel exhaust system once or twice during their
ownership of the car, rather than pay for a
replacement system which costs perhaps three times
that of a standard, mild steel system.
On the other hand, catalytic converters require
relatively high temperatures for efficient operation.
If a catalytic converter does not reach a minimum
temperature, the catalytic reactions therein will be
greatly reduced. Thus, most catalytic converters are
constructed of relatively costly materials in order to
withstand the heat generated therein. Even so, most
converters are installed at some distance from the
engine, in order to preclude being subjected to
excessive heat which could damage them.
While mufflers are generally installed toward the
extreme downstream end of the exhaust system, many
exhaust systems also incorporate a resonator.
Resonators are also sound attenuation devices, but
operate on a completely different principle than that
of the muffler. The muffler is adapted to cancel most
sounds therein by reflecting the sounds (and the
exhaust) back and forth through a series of parallel
pipes therein, and by forcing the exhaust gases
laterally outwardly through relatively small passages
in the pipes. The resonator is adapted to pass the
. exhaust gases therethrough . with little or no
impedance, while canceling or absorbing sounds within
a certain relatively well defined frequency range.
This range is generally relatively high, with the
muffler being relied upon for the attenuation of lower
exhaust frequencies.
As the resonator is adapted to attenuate different
frequencies than the muffler, and operates on a
different principle, it is generally placed elsewhere
in the exhaust system, somewhat forwardly of the
muffler. This is also the general area in which
catalytic converters are typically installed in an
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automobile, in order to avoid excessive exhaust heat
while still accepting sufficient exhaust heat to
function. While resonators do not generate internal
heat due to chemically reacting the exhaust products,
as do catalytic converters, they still must be
structured to accept a relatively high exhaust
temperature due to their location relatively near the
engine. However, heretofore no combining of a
catalytic converter and a resonator has been
accomplished, to the knowledge of the present
inventor.
Accordingly, a need will be seen for a catalytic
converter and resonator combination which serves both
purposes in a single device. The device may be
installed in a conventional automobile exhaust system,
between the engine and a conventional muffler and/or
tailpipe. Different embodiments may be provided for
single and dual exhaust systems, each of which may
include one or more catalytic converter elements or
~~bricks.~~ When used with a pre-catalytic converter,
a muffler for further sound attenuation may not be
required, depending upon the particular automobile,
engine, and exhaust system. A discussion of the
related art of which the present inventor is aware,
and its differences and distinctions from the present
invention, is provided. below.
U. S. Patent No. 4,050,903 issued on September 27,
1977 to Charles H. Bailey et al. describes a
Combination Muffler And Catalytic Converter, having a
relatively convoluted exhaust gas flow path
therethrough. The exhaust gases enter through a
venturi, which is used to draw air into the exhaust to
mix therewith. (It is noted that mufflers are
inherently pressurized somewhat higher than ambient
when in operation, due to the backpressure created in
such devices, yet Bailey et al. do not utilize any
other means than the venturi effect to introduce the
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air into the muffler.) The exhaust and air are mixed
by a deflector cone extending into the outlet of the
venturi. From this point, the exhaust mixture passes
through a series of holes in a transverse plate, and
5 thence through holes in another plate to enter the
catalytic converter. The present catalytic converter
and resonator combination is a straight through, axial
flow, free flow configuration, adapted for the
attenuation of specific frequencies, unlike the
muffler configuration of Bailey et al. Also, the
catalytic converter element of the present invention
is located within the forward portion of the device,
where it is subjected to the highest possible exhaust
heat which occurs within the entire device. Bailey et
al. locate their catalytic converter element in the
rearward portion of the device, where the exhaust
gases have cooled somewhat by their passage through
the convoluted flow path of the forward muffler
portion of the device. As the muffler itself is
generally located to the rear of the exhaust system,
some efficiency would be lost in the Bailey et al.
device, due to the relatively cooler exhaust
temperatures by the time the exhaust gases arrive at
the catalytic converter element.
U. S. Patent No. 4,425,304 issued on January 10,
1984 to Masayuki Kawata et al. describes a Catalytic
Converter comprising a single shell or container with
two converter units or "bricks" installed in series
therein. No sound attenuating means is disclosed by
Kawata et al. in their catalytic converter.
U. S. Patent No. 4,426,844 issued on January 24,
1984 to Keiichi Nakano describes an Engine Muffler Of
Heat-Exchanging Type, incorporating a pair of
catalytic converter components therein. The two
catalytic converter components are positioned in front
of the heat exchanger, which also acts as a muffler.
Exhaust gas flow enters the device by means of a
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radial pipe, and flows radially to enter and exit the
myriad of axial heat exchange passages in the muffler
and heat exchanger element. In contrast, the present
invention provides for strictly straight through,
axial flow of exhaust gases therethrough, in order to
reduce back pressure therein and provide the greatest
possible free flow of the exhaust gases. The present
device is not a muffler, with a convoluted and
restrictive flow path, but rather is a resonator,
adapted for the reduction or canceling of certain
specific exhaust gas frequencies.
U. S. Patent No. 5, 043, 147 issued on August 27, 1991
to Glen Knight describes a Combined Muffler And
Catalytic Converter Exhaust Unit, with a pair of
converters being installed within the first portion of
the muffler shell. The exhaust gases are then forced
to travel a sinusoidal, convoluted path forward and
aft through the muffler portion, with gases being
exchanged between various pipes within the muffler
portion due to perforations provided through the
pipes. The present straight through, free flow
resonator provides greatly reduced back pressure, in
comparison to a muffler configuration such as the
Knight apparatus. The disadvantages of including
catalytic converters within a muffler located toward
the outlet end of the exhaust system, with its reduced
heat, have been noted further above in the discussion
of the patent to Bailey et al., and apply here as
well.
U. S. Patent No. 5,108,716 issued on April 28, 1992
to Kimiyoshi Nishizawa describes a Catalytic Converter
having two converter components housed within a single
container or shell. No sound attenuation means is
disclosed by Nishizawa, as provided by the present
catalytic converter and resonator combination.
U. S. Patent No. 5,265,420 issued on November 30,
1993 to Erwin Rutschmann describes an Exhaust System
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Of A Multi-Cylinder Reciprocating Engine, in which a
single catalytic converter is provided for each
cylinder bank of a V-8 engine. Exhaust gases pass
through the two catalytic converters, thence to a
single transverse muffler. Thus, Rutschmann requires
three separate housings or units for the two catalytic
converters and single muffler of his system, whereas
the present catalytic converter and resonator
combination are combined within a single housing.
Also, the Rutschmann system does not provide straight
through flow, but requires the exhaust gases to make
several turns between the catalytic converters and the
transverse muffler inlet and outlet. No resonator is
disclosed by Rutschmann.
U. S. Patent No. 5,325,666 issued on July 5, 1994 to
Erwin Rutschmann describes an Exhaust System Of An
Internal Combustion Engine, somewhat similar to the
apparatus of the '420 U. S. Patent to the same
inventor, discussed immediately above. The convoluted
routing of the exhaust gases, the use of separate
housings or components for the catalytic converters
and mufflers, the use of a plenum around the catalytic
converters, and other differences, make the Rutschmann
apparatus distinct from the present catalytic
converter and resonator combination. Again, it must
.be noted that a muffler is not a resonator, and does
not provide straight through flow of exhaust gases and
the attenuation of a relatively narrow range of
frequencies.
U. S. Patent No. 5,378,435 issued on January 3, 1995
to Albino Gavoni describes a Silencer Combined With
Catalytic Converter For Internal Combustion Engines
And Modular Diaphragm Elements For Said Silencer. The
device is essentially a cylindrical container with a
series of cup-shaped catalytic converter elements
arranged therein. The elements are each relatively
thin, due to the cup-like shape of each element, and
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thus do not present a significant cross sectional area
to the exhaust gases passing therethrough. Thus, a
great many such elements are required, unlike the
present catalytic converter and resonator combination.
Moreover, the exhaust gas flow through the device, at
least at the entrance thereto, is not axial, but
passes radially through a plurality of lateral
openings in a conical inlet pipe, unlike the straight
through, axial flow configuration of the present
system.
U. S. Patent No. 5,398,504 issued on March 31, 1995
to Tomotaka Hirota et al. describes a Layout Structure
Of Catalytic Converters, in which first and second
converters are installed immediately adjacent the
respective cylinder banks of a V-configuration engine.
A separate third, main converter is provided beneath
the engine. Each of the converters is contained in a
separate housing or shell, unlike the combined
catalytic converter and resonator of the present
invention. Moreover, Hirota et al. do not disclose
any form of exhaust silencing or noise attenuating
means in their system, as is provided by the present
catalytic converter and resonator combination.
Japanese Patent Publication No. 55-43262 published
on March 27, 1980 illustrates an exhaust gas purifier
. in which the catalytic converter unit includes a
baffle within its inlet end to preclude interference
between exhaust gases alternatingly entering the
converter from the no. 1 and no. 4 cylinders, and the
no. 2 and no. 3 cylinders. No muffler, resonator, or
other sound attenuating means is apparent, as is
provided in the present catalytic converter and
resonator combination invention.
Finally, Japanese Patent Publication No. 57-41414
published on March 8, 1982 illustrates a method of
manufacturing a catalytic converter equipped with a
muffler. The assembly includes a forward muffler with
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a catalytic converter welded thereto and downstream
thereof, with a rear muffler welded to the downstream
end of the catalytic converter. The present catalytic
converter and resonator combination utilizes a single,
monolithic shell enclosing both the catalytic
converter and resonator components, with no welding of
separate components being required to form the housing
or shell for the device . A "protector 37 ~~ (per the
English abstract), apparently comprising an outer
shell spaced apart from the inner housing containing
the catalytic converter, is welded over the remainder
of the assembly, unlike the present catalytic
converter and resonator combination with its single
shell or housing. No disclosure is apparent regarding
any provision for a straight through, free flow
resonator, as provided by the present invention.
None of the above inventions and patents, either
singly or in combination, is seen to describe the
instant invention as claimed.
SUI~iARY OF THE INVENTION
The present invention comprises a catalytic
converter and resonator combination, combined within
a single canister or shell. The combination device
may be installed between the engine and a muffler at
or near the downstream or exhaust outlet end of the
exhaust system, with the system perhaps including an
additional catalytic converters) upstream of the
catalytic converter and resonator combination. The
placement of the present catalytic converter and
resonator combination forward of the muffler and
tailpipe of the exhaust system, with the converter
element forward of the resonator element, ensures that
the converter portion of the combination will receive
exhaust gases at a sufficiently high temperature to
produce the desired catalytic reaction and thereby
oxidize and/or reduce the exhaust components to
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harmless products. The catalytic converter element
may be formed of a thin wall ceramic material, for
further efficiency.
The resonator portion of the present combination is
5 a straight through, free flow configuration, with all
components being concentric to one another in the
single exhaust configuration for greater efficiency.
The resonator includes a central pipe with a plurality
of relatively small holes or passages therethrough,
10 for attenuating or canceling a relatively narrow band
of frequencies produced by the engine exhaust. An
alternative embodiment may include a dual exhaust
version, with two side by side resonator pipes behind
the catalytic converter portion, and either embodiment
I5 may include one or more catalytic converter elements
therein.
As noted above, a resonator operates on the
principle of canceling or impeding certain frequencies
of sound within a relatively narrow band or range.
The loudest sounds produced by various internal
combustion engines will vary in frequency, depending
upon the engine configuration (number of cylinders,
cylinder layout, etc.), and other factors, including
installation, etc. Accordingly, it is important to be
able to adjust or tune a resonator for a given
installation, in order to attenuate sounds within a
predetermined range. The present combination
catalytic converter and resonator invention may be
structured to provide for such adjustment at the time
of manufacture or assembly, as desired. Also,
additional sound absorbing material may be installed
within the device if desired, surrounding the inner
resonator pipe or tube, to absorb sounds which might
otherwise be transmitted through the outer shell of
the device.
Accordingly, it is a principal object of the
invention to provide an improved catalytic converter
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and resonator combination comprising a straight
through, axial f low, free f low conf igurat ion having at
least one catalytic converter element in the forward
portion thereof, with a concentric resonator pipe
positioned behind the at least one catalytic converter
component.
It is another object of the invention to provide an
improved catalytic converter and resonator combination
which catalytic converter element may have a substrate
formed of a strong and heat resistant thin wall
ceramic material.
It is a further object of the invention to provide
an improved catalytic converter and resonator
combination which may alternatively comprise a dual
exhaust configuration, with two side by side resonator
pipes disposed behind one or more catalytic converter
elements within a single monolithic shell.
An additional object of the invention is to provide
an improved catalytic converter and resonator
combination which may include one or more catalytic
converter elements concentrically in series therein.
Still another object of the invention is to provide
an improved catalytic converter and resonator
combination which may be adjusted or tuned at the time
of assembly to attenuate sounds in a specific
predetermined range, and which may include. further
sound absorbing materials therein to reduce sound
transmission through the shell thereof.
It is an object of the invention to provide improved
elements and arrangements thereof in an apparatus for
the purposes described which is inexpensive,
dependable and fully effective in accomplishing its
intended purposes.
These and other objects of the present invention
will become apparent upon review of the following
specification and drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view in partial section of
a single exhaust catalytic converter and resonator
combination of the present invention, showing its
structure and features.
Figure 2 is a perspective view in partial section of
an alternative embodiment of the device of Figure 1,
showing the adjustability of the inner resonator tube
during assembly for attenuating a predetermined range
or band of sound frequencies, and including further
sound absorbing materials therein.
Figure 3 is a perspective view in partial section of
an alternative embodiment of the single exhaust
catalytic converter and resonator combination of
Figure 1, incorporating dual concentric catalytic
converter elements therein.
Figure 4 is a perspective view in partial section of
another alternative catalytic converter and resonator
combination, with two side by side resonators behind
a single catalytic converter.
Figure 5 is a perspective view in partial section of
an alternative embodiment of the device of Figure 4,
incorporating dual concentric catalytic converter
elements therein.
Figure 6 is a detailed front elevation view of the
.substrate element and flow passages. of the present
catalytic converter element showing the thinner walls
and larger passages therethrough.
Figure 7 is a detailed front elevation view of a
prior art substrate element for a catalytic converter,
showing the relatively thick walls and narrow passages
therethrough.
Figure 8 is a flow chart showing the preferred
installation of the present catalytic converter and
resonator combination in an exhaust system.
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Similar reference characters denote corresponding
features consistently throughout the attached
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention comprises several different
embodiments of a catalytic converter and resonator
combination. The present invention includes at least
one (or more) catalytic converter elements) within
the same canister or shell used to house an exhaust
resonator, which is normally used for the attenuation
or canceling of exhaust noise or sound in a relatively
narrow frequency range. Such resonators generally
include a plurality of relatively small perforations
therein, with the size of the perforations being
configured according to the frequency or frequencies
which are to be attenuated or canceled. Resonators
are not mufflers, in that they do not serve to
attenuate or cancel a broad range of exhaust
frequencies, but rather reduce or eliminate certain
objectionable frequencies or levels which are more
difficult to attenuate using a conventional muffler.
Such resonators, if used, are generally installed in
an exhaust system forwardly of the conventional
muffler, between the muffler and the engine exhaust
manifold or catalytic converter downstream (i. e., in
. the direction of exhaust gas flow) from the manifold.
Accordingly, resonators accept a fair amount of
exhaust heat, somewhat more than that seen by the
muffler near the outlet end of the exhaust system. As
catalytic converters require a certain minimum amount
of heat for efficient operation of the catalytic
reactions) occurring therein, the present invention
combines at least one catalytic converter with a
resonator, where the converter may receive a
reasonable amount of exhaust heat.
A first embodiment of the present catalytic
converter and resonator combination is shown in Figure
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1, and is designated by the reference numeral 10. The
embodiment 10 of Figure 1 comprises a hollow,
monolithic tubular canister or shell 12, having a
forward or inlet end 14, a forward portion 16
immediately behind and adj acent the inlet end 14 , a
rearward portion 18 immediately behind and adjacent
the forward portion 16, and a rear or outlet end 20
immediately behind and adjacent the rearward portion
18. The forward portion 16 has an inner diameter 22
which is dimensioned to accept at least one catalytic
converter element 24 therein, with the catalytic
converter element 24 installed therein having an outer
diameter (also designated by the reference numeral 22)
substantially equal to the inner diameter 22 of the
canister 12. The rear portion 18 of the canister 12
has an inner diameter 26 dimensioned to accept a
resonator element therein.
The catalytic converter element 24 includes a
substrate 28 having a plurality of longitudinal
passages 30 therethrough, with each of the passages 30
being defined by a plurality of walls 32, as shown in
detail in Figure 6. These walls 32 may be generally
horizontally and vertically oriented to form a
honeycomb or grid-like configuration when viewed in
lateral cross section, as shown in Figure 6. Each of
the walls 32 is coated with one or more catalytically
reactive elements or materials, e. g., noble metals
such as platinum, palladium, rhodium, etc., as is
known in the art.
The efficiency of the present converter 24 is
increased by constructing the substrate 28 with the
walls 32 having a relatively thin cross section and
the passages 30 therebetween being relatively wide, in
order to reduce the restriction to exhaust gas flow as
much as possible. A comparison of the present
substrate 28 with a prior art substrate S shown in
Figure 7, clearly shows the wider passages 30 of the
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present substrate 28. The walls W of conventional
substrates, such as the substrate S shown in Figure 7,
are relatively thick due to the need for structural
strength at the elevated temperatures occurring within
5 catalytic converters. These walls W are normally
somewhat thicker than required for structural strength
at normal temperatures, but due to the extremely
elevated temperatures occurring within a catalytic
converter, they must be made even thicker to provide
10 the required structural strength at such elevated
temperatures where most materials are weakened.
The relative thickness of the walls W of
conventional catalytic converter substrates S results
in the passages P therebetween having a relatively
15 narrow width, as may be seen in a comparison of a
conventional catalytic converter substrate cross
section in Figure 7 and the substrate 28 of the
present catalytic converter and resonator invention.
Typically, such conventional passages P have a width
on the order of .040 inch, for a passage cross
sectional area of about .0016 inch. Wider passages,
with the walls therebetween being spaced further
apart, would not provide the required structural
strength at the elevated temperatures occurring within
such conventional catalytic converters.
On the other.hand, the catalytic converter substrate
28 of the present catalytic converter and resonator
combination 10 has passage widths substantially
greater than .040 inch, preferably on the order of
.050 inch for a passage cross sectional area of .0025
inch, or over half again as great an area as the
conventional catalytic converter passage P. Yet, the
number of passages 30 in a given cross sectional area
of the present substrate 28 closely approaches that of
the passages P in a conventional converter substrate
S, due to the relatively thin substrate walls 32 of
the present converter substrate 28. Due to their
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relatively high surface area per pass and volume
ratio, the thin substrate walls 32 serve to absorb
heat more quickly than the relatively thick walls W of
prior art substrates S. This allows the present
catalytic converter element 24 to reach its normal
operating temperature more quickly than catalytic
converters of the prior art, thus reducing the "cold
start" period when emissions are relatively high due
to the need for exhaust gases to warm up the converter
to reach an optimum temperature for the catalytic
reactions to occur efficiently. Thus, the catalytic
converter 24 of the present catalytic converter and
resonator combination 10 reduces the period of time
following a cold start when exhaust emissions are
relatively high due to the catalytic converter being
relatively cool.
While conventional converter substrates S have been
formed of relatively expensive metals in order to
provide the required structural strength at the
elevated temperatures found in such devices, the
catalytic converter 24 of the present catalytic
converter and resonator combination 10 preferably uses
a ceramic material for the substrate walls 32. Such
ceramic materials provide excellent resistance to
heat, but a relatively strong material is required in
order to provide the required structural strength,
particularly in the case of the relatively thin
substrate walls 32 of the present invention. A
ceramic material known as Dow-Corning XT (tm),
manufactured by the Dow-Corning Company, has been
found to be suitable for the construction of such thin
wall catalytic converter substrates 28 of the present
invention. Other materials providing sufficient
structural strength at the elevated temperatures
experienced within an operating catalytic converter,
may be used as desired.
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The canister rearward portion 18 includes a
resonator element 34 installed therein. The resonator
element 34 is a generally tubular or cylindrical
device, which may be rolled from a flat sheet of
suitable metal or otherwise formed. The resonator
element 34 has a hollow core 3&, a forward end 38, an
opposite rearward end 40, and an outer diameter 42
which is substantially less than the inner diameter 26
of the rear portion 18 of the canister 12. This
difference between the inner diameter 26 of the
canister rearward portion 18 and the outer diameter 42
of the resonator element 34, defines a sound
attenuating plenum 44 therebetween.
The resonator element 34 includes a plurality of
sound attenuating perforations 46 formed radially
therethrough, for the attenuation of exhaust sound in
a relatively narrow range of frequencies. The
passages or perforations 46 may be dimensioned and
spaced to accommodate different frequency ranges as
desired, as is known in the art.
The resonator element 34 is secured concentrically
within the canister rearward portion 18 by a forward
plate 48 and opposite rearward plate 50, affixed
respectively to the forward end 38 and rearward end 40
of the resonator tube 34 and within the rearward
.portion 18 of the canister 12, normal to the axis of
the resonator pipe 34 and canister 12. These two
plates 48 and 50 are toroid shaped, to allow exhaust
gases to pass from a plenum 52 disposed between the
catalytic converter element 24 and the forward end 38
of the resonator tube element 34, through the central
passage of the forward plate 48 and thence through the
hollow core 36 of the resonator pipe element 34 and
out through the central passage of the rearward plate
50, as indicated by the exhaust gas arrows G.
The essentially equal diameters 22 of the catalytic
converter element 24 and inner surface of the forward
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portion 16 of the canister 12 serve to affix the
catalytic converter element 24 concentrically within
the canister 12. The tight fit of the catalytic
converter element 24 within the forward portion 16 of
the canister 12, provides a tight seal between the
catalytic converter element 24 and forward portion 16
of the canister 12, thereby precluding any bypass flow
of exhaust gases therebetween.
The toroidal plates 48 and 50 serve to secure the
resonator pipe element 34 concentrically within the
rearward portion 18 of the canister 12, with the tight
fit of the catalytic converter element 24 within the
forward portion 16 of the canister 12 serving to
secure the converter element 24 concentrically
therein. Thus, it will be seen that all of the above
elements, i . a . , the canister 12 with its inlet and
outlet ends 14 and 20, catalytic converter 24, and
resonator element 34 with its hollow core 36, are
disposed concentrically relative to one another and
are axially aligned with one another to provide a
straight through, low restriction, free flow path for
engine exhaust through the catalytic converter and
resonator combination 10.
As noted further above, the resonator portion 34 of
the present invention functions by attenuating sound
of a predetermined frequency .range, by means of the
relatively small perforations 46 therethrough, and
nearly all of the exhaust gases G pass through the
resonator pipe hollow core 36. However, depending
upon the relative pressures between the resonator core
36 and the resonator plenum 44, some exhaust gases may
flow into the plenum 44. Accordingly, the rearward
resonator attachment plate 50 may include one or more
generally peripheral passages 54 therethrough, for
allowing exhaust gases to depart the resonator plenum
44 and exit the canister 12 from the outlet end 20
thereof. The forward resonator attachment plate 48
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may be formed with a solid periphery, to preclude the
flow of exhaust gases from the converter and resonator
plenum 52, directly into the resonator plenum 44.
As noted further above, resonators serve to
attenuate sounds in only a relatively narrow band or
range of frequencies, depending upon their
construction. The range of frequencies damped by a
given resonator, is primarily dependent upon the
length of the internal resonator element or pipe
therein, with shorter elements resulting in the
control of relatively higher frequencies, and longer
elements being adapted for the reduction of relatively
lower frequencies. As the predominant frequencies
emitted by a given internal combustion engine will be
dependent upon the configuration of the engine, it
will be seen that it is desirable to provide some
means for adjusting a resonator configuration for a
given installation. Such adjustability may be
important even for different resonators to be used
with identical engines in identical exhaust systems,
but in different vehicles, due to different resonant
qualities of the specific vehicle structure.
Accordingly, the present invention provides for
adjustment or tuning of the resonator frequency
response band, by means of the combination catalytic
converter and resonator.60 of Figure 2. The converter
and resonator combination 60 is constructed similarly
to the converter and resonator combination 10 of
Figure 1, having a hollow, monolithic tubular canister
or shell 62 with a forward or inlet end 64, a forward
portion 66 immediately behind and adjacent the inlet
end 64, and a rearward portion 68 immediately behind
and adjacent the forward portion 66. However, the
rearward portion 68 terminates in a conical section
70, which has a minor diameter equal to the diameter
of the resonator element 72 therein.
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The forward portion 66 is essentially identical to
the forward portion 16 of the converter and resonator
combination device 10 of Figure 1, with the forward
portion 66 being dimensioned to hold and secure at
5 least one catalytic converter element 24 therein. The
element 24 of the device 60 of Figure 2 is identical
to the element 24 of the device 10 of Figure 1, having
a substrate 28 with a plurality of longitudinal
passages 30 therethrough defined by walls 32, as shown
10 in detail in Figure 6. The specific structural
details and materials of the catalytic converter 24
have been discussed in detail further above in the
discussion of the converter and resonator combination
10 embodiment of Figure 1, and need not be repeated
15 here.
The canister rearward portion 68 includes a
resonator element 72 installed therein, constructed
generally in the same manner as that described for the
resonator element 34 of the embodiment 10 of Figure 1.
20 The resonator element 72 of the embodiment 68 of
Figure 2 has a hollow core 74, a forward end 76, and
an opposite rearward end 78, which also comprises the
rear or outlet pipe for the converter and resonator
combination embodiment 60 of Figure 2. The forward
portion of the resonator element 72 is formed
essentially identically to the resonator element 34 of
the device 10 of Figure 1, having a plurality of
relatively small sound attenuating perforations or
passages 80 formed through the wall thereof. The
forward end 76 of the resonator 72 is secured
concentrically within the canister rearward portion 68
by a forward plate 82.
It will be seen that the rear portion of the
embodiment 60 of Figure 2 differs from that of the
embodiment 10 of Figure 1, in that there is no need
for a rearward resonator element support plate in the
embodiment 60 of Figure 2. As the resonator element
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72 extends rearwardly from the rear conical portion 70
of the shell 62, the rear portion 78 of the element 72
is supported by the smaller diameter, necked down end
portion 84 of the conical portion 70, and is welded at
that joint to provide a leakproof seal at the time of
manufacture or assembly. Accordingly, the rearward
portion 78 of the resonator tube 72 is devoid of
perforations, in order to provide a leakproof outlet
for exhaust gases passing through the device 60 and
onward to a trailing exhaust pipe (not shown
conventionally connected to the outlet end 78 of the
resonator pipe element 72.
The remainder of the catalytic converter ,and
resonator combination 60 of Figure 2 is constructed
similarly to the embodiment 10 of Figure 1, with the
resonator element 72 having an outer diameter
substantially less than the inner diameter of the rear
portion 68 of the canister 62. This difference
between the inner diameter of the canister rearward
portion 68 and the outer diameter of the resonator
element 72, defines a sound attenuating plenum 86
therebetween. A forward sound attenuating plenum 88
is also defined between the rear of the catalytic
converter element 24 and the forward end 76 of the
resonator element 72 and its supporting front plate
82, within the outer shell 62 of the combination
catalytic converter and resonator device 60.
The toroidal front plate 82, along with the necked
down rearward end 84 of the conical rearward portion
70 of the shell 62, serve to secure the resonator pipe
element 72 concentrically within the rearward portion
68 of the canister 62, with the tight fit of the
catalytic converter element 24 within the forward
portion 66 of the canister 62 serving to secure the
converter element 24 concentrically therein. Thus, it
will be seen that all of the above elements, i. e. ,
the canister 62 with its inlet end 64 and necked down
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rearward end 84, catalytic converter 24, and resonator
element 72 with its hollow core 74, are disposed
concentrically relative to one another and are axially
aligned with one another to provide a straight
through, low restriction, free flow path for engine
exhaust through the catalytic converter and resonator
combination 60, essentially in the manner of the gas
flow provided in the converter and resonator
combination device 10 of Figure 1.
Engine exhaust gases flow through the device 60 of
Figure 2 generally in the manner described for the
exhaust gas flow through the converter and resonator
10 of Figure 1, as indicated by the exhaust gas arrows
G. While the small perforations 80 are adapted to
attenuate sounds of a certain predetermined frequency
range, it will be seen that some exhaust gases G will
flow through these passages 80. However, this is of
no consequence, because as gas pressure equalizes
within the plenum 86 between the resonator element 72
and the outer shell 62, those gases will flow back
through the resonator perforations 80 to be entrained
in the exhaust gas flow G as it passes through the
resonator element 72.
The above described construction for the combination
catalytic converter and resonator combination 60 of
.Figure 2, provides a means of adjusting the length of
the resonator element 72 within the outer shell 62 of
the device 60 during manufacture or assembly. The
resonator forward end support plate 82 may be welded
or otherwise suitably secured to the forward end 76 of
the resonator element 72, and the assembly inserted
into the outer shell 62 of the device 60 before the
conical rearward end 70 is welded to the rearward end
68 of the outer shell or canister 62. At this point,
the rearward conical end 70 is welded in place, with
the rearward or outlet portion or end 78 of the
resonator tube element 72 extending outwardly past the
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smaller diameter trailing end 84 of the rearward
element 70 of the shell or canister 62.
It will be seen that at this point, the resonator
element 72 and its attached forward end support plate
82 may be adjusted or repositioned as desired axially
within the outer shell or canister 62, as indicated by
the adjustment arrow A in Figure 2. This allows the
resonator element 72 to be positionally adjusted to a
predetermined position as desired, in order to achieve
the attenuation of sound within a certain
predetermined frequency range. Extending the
resonator element 72 rearwardly from the rearward
portion 70 of the device 60 (with less of the element
72 residing within the plenum 86) results in the
attenuation of relatively higher frequencies, while
inserting the resonator element 72 into the interior
of the shell 62 results in the attenuation of
relatively lower frequencies.
The seam or joint defined by the smaller diameter
rearward end 84 of the conical rearward end 70 of the
outer shell or canister 62 and the unperforated end
portion 78 of the resonator element 72, is then welded
to provide a leakproof seal and to immovably affix the
resonator element 72 in place. Thus, the catalytic
converter and resonator combination device 60 of
Figure 2 , may be adj ustably .tuned for each specif is
engine and vehicle application for which it is
manufactured, in order to achieve the optimum sound
attenuation in the frequency range desired.
While the above described adjustment of the
resonator element 72 within the shell or canister 62
affects the attenuated frequency range of the device
60 to a great extent, it has very little, if any,
effect on the volume of sound which emanates from the
device 60. As there is no structure within the
toraidal plenum 86 surrounding the resonator element
72, there may be a certain amount of sound which
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radiates from the resonator element 72, through the
plenum 86, and outwardly through the walls of the
outer shell or canister 62. Accordingly, the plenum
volume 86 may be filled, at least to a certain degree
as desired, with a sound absorbing material 90, in
order to dampen the volume of sound which may emanate
from the device 60. Such material may comprise glass
fiber, corrosion resistant metal strands ("stainless
steel wool"), spun fibers or strands of a rock or
stone material such as basalt ("rock wool"), or other
suitable material which is capable of retaining its
structure when subjected to the high temperatures
occurring within the present device 60.
The above described embodiments each include a
single resonator tube element 34 or 72 with a single
catalytic converter element 24 concentric therewith.
However, it will be seen that additional catalytic
converter elements may be added in series with the
single element 24 of the devices 10 and 60
respectively of Figures 1 and 2, if so desired, for
further efficiency. Figure 3 discloses such an
alternate embodiment, designated as catalytic
converter and resonator combination 100.
The catalytic converter and resonator 100 is
constructed generally along the lines of the converter
and resonator 10 of Figure 1, comprising a canister or
shell 102 with an inlet end 104, forward portion 106,
rearward portion 108, and outlet end 110. The
canister forward portion 106 is actually divided into
two separate portions, respectively 112 and 114, each
having a catalytic converter, respectively 116 and
118, affixed therein, with each sealed about its
periphery in the manner of the single catalytic
converter 24 within the forward portion 16 of the
converter and resonator combination 10 of Figure 1.
The two catalytic converter elements 116 and 118 may
be spaced apart by a catalytic converter plenum 120
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disposed therebetween, if desired. Alternatively, the
two converters 116 and 118 may be positioned
immediately adjacent one another, in order to transfer
heat generated by the catalytic reactions therein to
5 one another for greater efficiency. A catalytic
converter and resonator plenum 122 may be provided
behind the second converter 118, in the manner of the
converter and resonator plenum 52 of the converter and
resonator 10 of Figure 1.
10 Each of the catalytic converter elements 116 and 118
includes a substrate, respectively 124 and 126. These
two substrates 124 and 126 are preferably formed in
the manner described further above for the substrate
28 of the catalytic converter 24 of Figure 1, i.e.,
15 having relatively thin walls and relatively large
passage widths therebetween, as illustrated in Figure
5. A ceramic material, such as the Dow-Corning XT
described further above, may be used to form the
substrates 124 and 126 of the embodiment 100 of Figure
20 2. If desired, the two substrates 124 and 126 may
utilize different coatings or washes of catalytic
materials or elements thereon, and/or in different
concentrations, in order to catalyze different exhaust
products to differing degrees in each of the two
25 converters 116 and 118. It will be seen that
additional catalytic converter elements, not shown,
may be placed in series with the two catalytic
converter elements 116 and 118 of the catalytic
converter and resonator combination 100 of Figure 3,
if so desired, for further efficiency in processing
exhaust emissions.
The rearward portion 108 of the canister 102
contains an axially concentric resonator tube or pipe
element 128 having a plurality of noise attenuating
perforations 130 therein. The resonator element 128
is affixed within the canister rearward portion 108 by
a forward and a rearward toroidal plate, respectively
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132 and 134, as in the converter and resonator
combination 10 of Figure 1. A resonator plenum 136 is
defined between the resonator element 128 and the
canister rearward portion 108, similar to the
equivalent construction shown in Figure 1.
As in the catalytic converter and resonator
combination 10 of Figure 1, the forward resonator tube
retaining plate 132 is preferably formed with a solid,
impermeable periphery, to preclude exhaust gases from
flowing directly into the resonator plenum 136 from
the catalytic converter and resonator plenum 122.
However, the rear retaining plate 134 may be provided
with a series of peripheral passages 138 therethrough,
in the manner of the rear plate 50 of the converter
and resonator combination 10 of Figure 1, in order to
allow any small amount of gases passing into the
resonator plenum 136 to escape therefrom.
The catalytic converter and resonator combination
100 of Figure 3 functions essentially like the
converter and resonator 10 of Figure Z, with exhaust
gases G entering the canister 102 through the inlet
end 104, and thence passing through the two catalytic
converters 116 and 118. The converters 116 and 118
(and/or others) serve to react the exhaust gases G
catalytically, whereupon the gases G pass into the
catalytic converter and resonator plenum. 122 and
rearwardly through the resonator element 128. The
noise level of the exhaust is canceled or attenuated
in a frequency range (generally relatively higher
frequencies) according to the spacing and dimensions
of the perforations 130 of the resonator element 128.
The gases G then exit the catalytic converter and
resonator combination 100 from the rear or outlet end
110 of the canister 102, to pass into the remainder of
the exhaust system.
Figures 4 and 5 illustrate two further embodiments
of the present invention, for dual exhaust systems
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having a pair of inlet pipes and a corresponding pair
of outlet pipes. The catalytic converter and
resonator of Figure 4, designated by the reference
numeral 200, will be seen to have a single catalytic
converter element therein, but includes a pair of
resonator elements. The catalytic converter and
resonator 200 is constructed somewhat along the lines
of the converter and resonator 10 of Figure 1,
comprising a canister or shell 202 with an inlet end
204, forward portion 206, rearward portion 208, and
outlet end 210. However, it will be seen that the
inlet and outlet ends 204 and 210 each respectively
comprise a pair of laterally joined, truncated,
conically shaped shells blending together to smoothly
join the oval shaped canister portion 202. The inlet
and outlet ends 204 and 210 each have a pair of
cylindrical inlet and outlet pipes, respectively 212
and 214, extending therefrom. These twin inlet and
outlet pipes 212 and 214 allow the catalytic converter
and resonator combination 200 of Figure 4, to be
installed in a dual exhaust system.
The catalytic converter element 216 of the converter
and resonator combination 200 of Figure 4, will be
seen to have an oval configuration closely fitting
within and sealed to the forward portion 206 of the
converter and resonator canister 202. Thus, exhaust
gases cannot pass between the inner wall of the
canister 202 shell and the outer wall of the catalytic
converter element 216, but must pass through the
substrate 218, as in the manner of the other
embodiments.
The substrate 218 of the catalytic converter element
216 is preferably constructed similarly to the
substrates 28, 124, and 126 of the converter and
resonator devices 10 and 100 discussed further above,
i. e., preferably formed of a ceramic material such as
Dow-Corning XT (tm), with relatively thin walls to
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allow the substrate to heat rapidly for maximum
efficiency, and with relatively wide passages
(preferably greater than .040 inch) therethrough for
reducing exhaust gas flow restriction as much as
possible. A catalytic converter and resonator plenum
220 may be provided behind the converter element 216,
in the manner of the converter and resonator plenum 52
of the converter and resonator 10 of Figure 1.
The canister rearward portion 208 contains first and
second laterally spaced, axially concentric resonator
pipe elements, respectively 222 and 224, each having
a plurality of noise attenuating perforations 226
therein. The resonator elements 222 and 224 are
affixed within the canister rearward portion 208 by a
forward and a rearward plate, respectively 228 and
230, as in the converter and resonator combination 10
of Figure 1. Instead of the toroid shaped plates of
the catalytic converter and resonator combinations 10
and 100 of Figures 1 and 3, the two plates 228 and 230
each have an oval peripheral shape, to fit closely
within the oval shaped canister 202. Each plate 228
and 230 includes a pair of laterally spaced apart
resonator passages therethrough, for exhaust gases to
pass from the converter and resonator plenum 220 into
the two resonator elements 222 and 224, and from the
resonator elements 222 and.224, into the canister
outlet portion 210.
A resonator sound attenuating plenum 232 is defined
between the first and second resonator elements 222
and 224 and the canister rearward portion 208, similar
to the equivalent construction shown in Figure 1. The
plenum 232 of the converter and resonator combination
200 of Figure 4 serves essentially the same function
as the plenum 44 of the device 10 of Figure 1, i. e.,
to attenuate exhaust noise or sound of a predetermined
frequency range, before the exhaust gases leave the
device. However, it will be noted that the plenum 232
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of the device of Figure 4 is somewhat larger than that
of the other two converter and resonator combination
devices 10 and 100 described further above, since the
surrounding canister 202 does not encircle only a
single resonator element.
The resulting relatively large plenum 232 may be
desirable, with pressure waves from the two resonator
elements 222 and 224 perhaps canceling one another in
the central area of the plenum 232 between the two
resonator tubes 222 and 224. However, it is possible
that amplification of certain frequencies might also
occur under certain conditions, and accordingly, it
may be desirable to divide the single large plenum 232
with a longitudinal baffle 234 (shown as an optional
component, in broken lines in Figure 4) in order to
separate the two resonator elements 222 and 224. The
baffle 234 may extend forwardly of the forward
resonator attachment plate 228, if so desired, to
divide the converter and resonator plenum as well.
The forward resonator tube retaining plate 228 may
be formed with a solid, impermeable periphery, as in
the catalytic converter and resonator combination 10
of Figure 1. However, an alternative is shown in the
converter and resonator embodiment 200 of Figure 4, in
which both the front and rear plates 228 and 230
include a plurality of peripheral passages,
respectively 236 and 238, therethrough, in the manner
of the rear plate 50 of the converter and resonator
combination 10 of Figure 1, in order to allow any
small amount of gases passing into the resonator
plenum 232 to escape therefrom.
The catalytic converter and resonator combination
200 of Figure 4 functions essentially like the
converter and resonator 10 of Figure 1, with exhaust
gases G entering the canister 202 through the dual
inlet pipes 212 of the inlet end 204, and thence
passing through the single catalytic converter element
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216. (While the single oval shaped converter element
216 is generally shaped to fit more conventional
catalytic converters, it will be seen that the dual
resonator embodiment 200 of Figure 4 could be
S constructed with the forward portion 206 of the
canister 202 configured with two adjacent
cylindrically shaped areas, to accept two laterally
spaced cylindrical converter elements configured
somewhat like the converter elements 24, 116, and 118
10 of Figures 1 and 2, if so desired.)
The converter element 216 serves to react the
exhaust gases G catalytically, whereupon the gases G
pass into the catalytic converter and resonator plenum
220 and rearwardly through the two resonator elements
15 222 and 224. The noise level of the exhaust is
canceled or attenuated in a frequency range (generally
relatively higher frequencies) according to the
spacing and dimensions of the perforations 226 of the
two resonator elements 222 and 224, and the
20 installation of a dividing baffle 234 (if any)
therebetween. The gases G then exit the catalytic
converter and resonator combination 200 from the rear
or outlet end 210 and corresponding outlet pipes 214
of the canister 202, to pass into the remainder of the
25 exhaust system.
The axially parallel configuration of the inlet
pipes 212, substrate passages of the catalytic
converter element 216, dual resonator elements 222 and
224, and outlet pipes 214, serve to provide the least
30 possible change of direction for exhaust gases G
flowing through the catalytic converter and resonator
combination 200 of Figure 4. In fact, other than some
mixing and expansion which may occur in the plenums of
the device 200 of Figure 4, the components of the two
basic exhaust gas passages defined by each
corresponding inlet and outlet pipe 212 and 214, are
precisely axially aligned with one another.
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Preferably, the canister shell 202, resonator elements
222 and 224 , forward and rearward resonator attachment
plates 228 and 230, and longitudinal resonator plenum
baffle 234 (if installed) are all formed of corrosion
resistant (stainless) steel, although other materials
may be used if desired.
The catalytic converter and resonator combination
embodiment 300 of Figure 5, will be seen to be similar
to the converter and resonator combination embodiment
200 illustrated in Figure 4 and discussed above, and
closely related to the catalytic converter and
resonator combination embodiments 10, 60, and 100,
respectively of Figures 1, 2, and 3. However, rather
than having only a single oval shaped converter
element installed in the forward portion of the
canister, the converter and resonator combination 300
of Figure 5 includes a pair of catalytic converter
elements in tandem, somewhat along the lines of the
catalytic converter and resonator combination device
100 illustrated in Figure 3.
The catalytic converter and resonator 300 is
constructed somewhat along the lines of the converter
and resonator 200 of Figure 4, comprising a generally
oval shaped canister or shell 302 with an inlet end
304, forward portion 306, rearward portion 308, and
outlet end 310. However, it will be seen that the
inlet and outlet ends 304 and 310 each respectively
comprise a pair of laterally joined, truncated,
comically shaped shells blending together to smoothly
join the oval shaped canister portion 302. The inlet
and outlet ends 304 and 310 each have a pair of
cylindrical inlet and outlet pipes, respectively 312
and 314, extending therefrom. These twin inlet and
outlet pipes 312 and 314 allow the catalytic converter
and resonator combination 300 of Figure 5, to be
installed in a dual exhaust system.
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Rather than, the single catalytic converter elements
24 and 216 of the converter and resonator combination
embodiments 10, 60, and 200 respectively of Figures 1,
2, and 4, the canister forward portion 306 of the
catalytic converter and resonator combination 300 of
Figure 5 is actually divided into two separate
portions, respectively 316 and 318, each having a
catalytic converter element, respectively 320 and 322,
affixed therein. Each catalytic converter element 320
and 322 is sealed about its periphery in the manner of
the single catalytic converter 24 within the forward
portion 16 of the converter and resonator combination
10 of Figure 1, and other embodiments discussed
further above.
The two catalytic converter elements 320 and 322 may
be spaced apart by a catalytic converter plenum 324
disposed therebetween, if desired. Alternatively, the
two converters 320 and 322 may be positioned
immediately adjacent one another, in order to transfer
heat generated by the catalytic reactions therein to
one another for greater efficiency. A catalytic
converter and resAnator plenum 326 may be provided
behind the second converter 324, in the manner of the
converter and resonator plenum 52 of the converter and
resonator 10 of Figure 1.
It will be seen that the catalytic converter and
resonator combination embodiment 300 of Figure 5 may
be constructed to have a greater length for the
inclusion of additional catalytic converter elements
(not shown), if desired, in a similar manner to the
alternative construction of the catalytic converter
and resonator combination 100 of Figure 3, discussed
further above.
Each catalytic converter element 320 and 322
includes a substrate, respectively 328 and 330. These
two substrates 328 and 330 are preferably formed in
the manner described further above for the substrate
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28 of the catalytic converter 24 of Figure 1, i.e.,
having relatively thin walls and relatively large
passage widths therebetween, as illustrated in Figure
6. A ceramic material, such as the Dow-Corning XT
described further above, may be used to form the
substrates 328 and 330 of the embodiment 300 of Figure
5. If desired, the two substrates 328 and 330 may
utilize different coatings or washes of catalytic
materials or elements thereon, and/or in different
concentrations, in order to catalyze different exhaust
products to differing degrees in each of the two
converters 320 and 322. As noted further above,
additional catalytic converter elements, not shown,
may be placed in series with the two catalytic
converter elements 320 and 322 of the catalytic
converter and resonator combination 300 of Figure 5,
if so desired, for further efficiency in processing
exhaust emissions.
The two catalytic converter elements 320 and 322 of
the converter and resonator combination 300 of Figure
5, each have an oval configuration closely fitting
within and sealed respectively within the first and
second catalytic converter portions 316 and 318 of the
converter and resonator canister 302. Thus, exhaust
gases cannot pass between the inner wall of the
canister 302 shell and the.outer walls of the two
catalytic converter elements 320 and 322, but must
pass through the respective substrates 328 and 330, as
in the manner of the other embodiments.
The two substrate elements 328 and 330 of the
respective catalytic converter elements 320 and 322
are preferably constructed similarly to the substrates
28, 124, 126, and 218 of the converter and resonator
devices 10, 60, 100, and 200 discussed further above,
i. e., preferably formed of a ceramic material such as
Dow-Corning XT (tm), with relatively thin walls to
allow the substrate to heat rapidly for maximum
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efficiency, and with relatively wide passages
(preferably greater than .040 inch) therethrough for
reducing exhaust gas flow restriction as much as
possible.
The canister rearward portion 308 contains first and
second laterally spaced, axially concentric resonator
pipe elements, respectively 332 and 334, each having
a plurality of noise attenuating perforations 336
therein. The resonator elements 332 and 334 are
affixed within the canister rearward portion 308 by a
forward and a rearward plate, respectively 338 and
340, as in the converter and resonator combination 200
of Figure 4, and others. Instead of the toroid shaped
plates of the catalytic converter and resonator
combinations 10, 60, and 100 respectively of Figures
1, 2, and 3, the two plates 338 and 340 each have an
oval peripheral shape, to fit closely within the oval
shaped canister 302. Each plate 338 and 340 includes
a pair of laterally spaced apart resonator passages
therethrough, for exhaust gases to pass from the
converter and resonator plenum 326 into the two
resonator elements 332 and 334, and from the resonator
elements 332 and 334, into the canister outlet portion
310.
A resonator sound attenuating plenum 342 is defined
between the first arid second resonator elements 332
and 334 and the canister rearward portion 308, similar
to the equivalent construction shown in Figure 3. The
plenum 342 of the converter and resonator combination
300 of Figure 5 serves essentially the same function
as the plenum 232 of the device 200 of Figure 4, i.e.,
to attenuate exhaust noise or sound of a predetermined
frequency range, before the exhaust gases leave the
device. The plenum 342 of the device of Figure 5 is
configured much the same as the plenum 232 of the
converter and resonator combination 200 of Figure 4,
due to the similar configuration of the remainder of
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the two devices. A longitudinal baffle 344 (shown
optionally, in broken lines) may be installed between
the two resonator elements 332 and 334 to divide the
single large plenum 342, in the manner and for the
5 purposes of the optional baffle 234 of the catalytic
converter and resonator combination 200 shown in
Figure 4.
The forward resonator tube retaining plate 338 may
be formed with a solid, impermeable periphery, as in
10 the catalytic converter and resonator combination 10
of Figure 1. However, an alternative is shown in the
converter and resonator embodiment 300 of Figure 5, in
which both the front and rear plates 338 and 340
include a plurality of peripheral passages,
15 respectively 346 and 348, therethrough, in the manner
of the rear plate 50 of the converter and resonator
combination 10 of Figure 1, in order to allow any
small amount of gases passing into the resonator
plenum 342 to escape therefrom.
20 The catalytic converter and resonator combination
300 of Figure 5 functions essentially like the
converter and resonator 100 of Figure 3, with exhaust
gases G entering the canister 302 through the dual
inlet pipes 312 of the inlet end 304, and thence
25 passing through the two catalytic converter elements
320 and 322.. (While the two oval shaped converter
elements 320 and 322 are generally shaped to fit more
conventional catalytic converters, it will be seen
that the dual resonator embodiment 300 of Figure 5
30 could be constructed with the forward portion 306 of
the canister 302 configured with two adjacent
cylindrically shaped areas, to accept two laterally
spaced cylindrical converter elements configured
somewhat like the converter elements 24, 116, and 118
35 of Figures 1 and 3, if so desired.)
The converter elements 320 and 322 serve to react
the exhaust gases G catalytically, whereupon the gases
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G pass into the catalytic converter and resonator
plenum 326 and rearwardly through the two resonator
elements 332 and 334. The noise level of the exhaust
is canceled or attenuated in a frequency range
(generally relatively higher frequencies) according to
the spacing and dimensions of the perforations 336 of
the two resonator elements 332 and 334, and the
installation of a dividing baffle 344 (if any)
therebetween. The gases G then exit the catalytic
converter and resonator combination 300 from the rear
or outlet end 310 and corresponding outlet pipes 314
of the canister 302, to pass into the remainder of the
exhaust system.
The axially parallel configuration of the inlet
pipes 312, substrate passages of the two catalytic
converter elements 320 and 322, dual resonator
elements 332 and 334, and outlet pipes 314, provide
the least possible change of direction for exhaust
gases G flowing through the catalytic converter and
resonator combination 300 of Figure 5. In fact, other
than some mixing and expansion which may occur in the
plenums of the device 300 of Figure 5, the components
of the two basic exhaust gas passages defined by each
corresponding inlet and outlet pipe 312 and 314, are
precisely axially aligned with one another. As in the
case of the other embodiments discussed further above,
various sheet metal components are preferably formed
of corrosion resistant (stainless) steel, although
other materials may be used if desired.
A test of one of the dual resonator embodiments of
the present catalytic converter and resonator
combination was performed on August 12, 1997, to
measure the exhaust emissions from an engine E to
which the present invention was connected.
(Comparable results would be expected from the other
embodiments when installed in a compatible exhaust
system.) Testing was performed on an automobile (1992
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37
Marocco) using an engine from a 1992 Chevrolet
Corvette, with the engine meeting the emissions
regulations for that model year. The test
configuration was somewhat along the lines of the
assembly shown in Figure 8, with the converter and
resonator combination, e.g., embodiment 300, being
connected to the exhaust system of an engine E,
somewhat downstream of the engine E in the general
location of a conventional resonator installation.
A muffler M was installed at the downstream end of
the system. While a conventional pre-catalytic P and
catalytic converter C are shown in Figure 8, it should
be noted that these two components are not necessarily
required with the present catalytic converter and
resonator combination in any of its embodiments, but
may be installed therewith if so desired or required.
While the muffler M may be desirable for further noise
reduction, it should be noted that the combination of
the present catalytic converter and resonator, with
either a pre-catalytic converter and/or another
catalytic converter, may obviate need for further
noise reduction means, particularly if additional
sound absorbent material is installed. Test results
are provided in Table I, following.
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3 TABLE I. EXHAUST RESULTS
EMISSIONS TEST
TOTAL CARBON OXIDES OF NON-METHANE
HYDROCARBONS MONOXIDE NITROGEN HYDROCARBONS
1992 CALIF. 0.41 3.40 1.00 (Not tested
AIR RESOURCES in 1992)
BOARD STANDARDS
(grams/mile)
LOW EMISSIONS 0.41 3.40 0.20 0.075
VEHICLE
ULTRA LOW 0.41 1.70 0.20 0.040
EMISSIONS
VEHICLE
1992 CORVETTE 0.33 1.82 0.63 (Not tested
(90 seconds to in 1992)
closed loop)
1992 MAROCCO, 0.08 0.58 0.63 0.069
CATALYTIC
CONVERTER AND
RESONATOR
(240 seconds to
closed loop)
It should be noted that the 1992 Marocco is an
exotic, high performance automobile which uses the
engine and drivetrain components from a 1992 Chevrolet
Corvette, including the six speed manual transmission
of that drivetrain. This transmission includes a
"skip shift" pattern which electronically induces a
second gear lockout when the. car is shifted from first
gear at relatively low throttle openings and engine
speed, in order to meet the CAFE (Corporate Average
Fuel Economy) requirements without penalty. Thus, the
transmission is shifted from first to fourth gear,
rather than being sequentially shifted from first to
second gear.
However, the above noted test results for the 1992
Corvette did not use the skipped shift pattern during
the time the engine was not fully warm, but rather
used a sequential shift pattern. This enabled the
1992 Corvette to warm up more quickly, requiring only
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90 seconds to attain "closed loop" status with the
emissions control components being fully heated, to
meet the emissions standards as required. The 1992
Marocco utilized the skipped shift pattern, going from
first directly to fourth gear, throughout this test.
It appears that this caused the engine to warm more
slowly, resulting in the electronic controls for the
emissions requiring a full 240 seconds to attain
"closed loop" status, when the catalytic converter was
completely heated. This appears to be the cause for
the relatively high oxides of nitrogen emissions
component. Further testing is planned in order to
check this factor.
Another factor in the above test was an additional
catalytic converter component installed on the 1992
Marocco car, comprising a combination pre-catalytic
converter and catalytic converter device. An exhaust
and emissions system engineer was consulted and found
that the present catalytic converter and resonator
combination was responsible for about 30 percent of
the reduction in emissions of the car. Thus,
factoring out the approximately 70 percent emissions
reduction due to the pre-catalytic converter and
catalytic converter combination installed on the 1992
Marocco, would result in total hydrocarbon and carbon
monoxide emissions .respectively of 0.27 and 1.67
grams/mile, which still betters both the 1992 Corvette
emissions test results and the ultra low emissions
vehicle standards.
Although the test standards did not allow the 1992
Marocco car equipped with the present catalytic
converter and resonator combination to be measured by
the same standards as the 1992 Corvette, it should be
noted that with the exception of the oxides of
nitrogen emissions component, the system meets or
exceeds the standards for ultra-low emissions vehicles
planned for the future. Also, even though the testing
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of the 1992 Marocco was not conducted to the same
standards as that of the 1992 Corvette, the 1992
Marocco equipped with the present catalytic converter
and resonator combination, bettered the exhaust
5 emissions measured from the 1992 Corvette for total
hydrocarbons and carbon monoxide, even when factoring
out emissions reductions due to other emissions
control devices installed on the 1992 Marocco
automobile.
10 In summary, the present catalytic converter and
resonator combination result in superior exhaust
emissions control for an internal combustion engine.
The installation of one or more catalytic converter
elements with one or more resonator pipe elements, in
15 the area where such systems are typically installed
along the mid portion of an automobile exhaust system,
results in the catalytic converter elements)
receiving sufficient exhaust heat to provide
significant reductions in exhaust emissions, while
20 simultaneously controlling noise with the resonator
component. The present device may be used with other
exhaust emissions and noise control devices, or may be
used as a stand alone system, pending testing which
may find that further emissions and sound controls are
25 not required on certain automobiles and engines.
The present catalytic converter and resonator
combination in any of its embodiments may also be
constructed to provide for the adjustment or tuning of
the resonator element within the outer shell or
30 canister, at the time of manufacture or assembly. In
this manner, the present invention may be tuned to a
predetermined configuration in order for the resonator
to attenuate exhaust sounds in a predetermined
frequency range as desired, to suit specific engine
35 and/or vehicle configurations. Also, any of the
embodiments described herein may be provided with some
form of sound insulation material disposed within the
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41
plenum surrounding the resonator element(s), in order
to attenuate the volume of exhaust sound emanating
from the device.
The use of a strong and durable material which is
capable of withstanding extremely high temperatures,
enables the substrates of the present catalytic
converter components to be constructed with thinner
walls, and thus larger passages therethrough, to
reduce restrictions to exhaust gas flow through the
components. The relatively thin walls of the
substrates, with their relatively high surface area to
mass and volume ratios, allow them to heat up more
quickly to achieve further gains in catalytic reaction
efficiency. The effect of the present catalytic
converter and resonator combination invention, in any
of its embodiments, enables essentially conventional
internal combustion engines to meet or exceed the
standards set for ultra low emissions vehicles, and
will result in a cleaner, healthier environment when
motor vehicles are equipped with the system of the
present invention.
It is to be understood that the present invention is
not limited to the sole embodiments described above,
but encompasses any and all embodiments within the
scope of the following claims.
