Note: Descriptions are shown in the official language in which they were submitted.
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DIESEL EXHAUST CONDITIONING SYSTEM
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates generally to emissions
control systems for internal combustion engines, and
more specifically to an exhaust conditioning system
for diesel engines. The present system provides for
the reduction of oxides of nitrogen, carbon monoxide,
and unburned hydrocarbons, as well as the reduction of
carbon particulates in the diesel exhaust, using one
or more combination catalytic converters and
particulate filters. A shroud surrounds the catalytic
converter - filter and other components, to insulate
the system and reduce external temperatures.
2. DESCRIPTION OF THE RELATED ART
Exhaust emissions from internal combustion engines
are recognized to be a very serious environmental
hazard, and accordingly, numerous ever more stringent
laws and regulations require ever cleaner and purer
exhaust emissions from such engines. Regulations
directed to the diesel or compression ignition engine
have generally not been quite so strict as those
directed to spark ignition engines, due to the smaller
number of diesel engines in operation and also due to
the difficulty in reducing or eliminating the carbon
particulates normally emitted by such engines.
Nevertheless, the reduction of exhaust emission
products from diesel engines is important,
particularly for such engines which are used in
confined areas, such as generators in enclosed areas,
diesel powered machinery used in the underground
mining industry, etc. Obviously, it is critical that
exhaust emissions be minimized to the greatest degree
possible, particularly in the underground mining
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environment, where breathable air is absolutely
critical and toxic gases such as carbon monoxide
cannot be tolerated to any degree whatsoever.
Due to these factors, and the difficulty in reducing
exhaust emissions from diesel engines to the required
degree, many, if not most, jurisdictions either
prohibit or greatly restrict the use of diesel powered
machinery in underground mining operations. Those
that permit such diesel machinery to be used in
underground mining, require extremely strict emissions
control for such engines. The Pennsylvania Article
II-A Diesel Powered Equipment regulations, for
example, require that carbon monoxide emissions be
reduced to no more than 100 parts per million (ppm),
that carbon particulates be reduced by 950 or more
from their otherwise unrestricted output, and that
exhaust gas temperatures be reduced to no more than
150 degrees Celsius (302 degrees Fahrenheit). These
regulations have heretofore generally been considered
to be mutually exclusive, as the reduction of
emissions by means of a catalytic converter results in
considerable heat output from the converter due to the "
catalytic reaction which serves to clean the
emissions. Moreover, the particulate matter is
another problem altogether.
Various means have been attempted to resolve this
problem, with the solution generally being to cool the
reaction in some manner to reduce the temperatures,
while trapping the particulates in a separate filter
element or the like and cleaning or disposing of the
filter periodically. Water has been used as a
filtering element, but the resulting sludge creates a
maintenance headache and disposal problem, and water
per se does little or nothing to reduce other
emissions.
Accordingly, a need will be seen for a means of
reducing the exhaust emissions of a diesel engine,
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particularly an engine in an enclosed environment such
as an underground mine, and simultaneously reducing
the carbon particulate output and temperature of the
exhaust. The emissions and particulate reductions are
preferably accomplished by means of a single system,
rather than requiring separate catalytic converters
and filters, although multiple catalytic converter
units for treating different types of exhaust
pollutants might be used, if so desired. Moreover,
the temperature of the converters) and filters)
combination should be maintained at a sufficiently
high level so as to operate efficiently, with the
system still producing a relatively cool exhaust at or
below the above noted Pennsylvania requirements. A
discussion of the related art of which the present
inventor is aware, and its differences and
distinctions from the present invention, is presented
immediately below.
U. S. Patent No. 3,645,093 issued on February 29,
1972 to William L. Thomas describes an Air Pollution
Control System For Internal Combustion Engines,
comprising a combustion chamber into which unburned or
partially burned hydrocarbons and/or exhaust products
are passed. An air pump forces additional oxygen into
the chamber for further combustion of the exhaust
products, with an ignition source also being provided.
A separate coolant pump is used to circulate a liquid
coolant around the outside of the combustion chamber
shell. No catalytic converter is disclosed by Thomas.
The air pump does not provide any cooling for the
system, as does the axial fan of the present exhaust
system. Rather, the Thomas air pump creates
additional heat by providing further oxidation of
exhaust output, thus requiring Thomas to provide
cooling,for the system using some other means, i. e.,
liquid.
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U. S. Patent No. 3,820,327 issued on June 28, 1974
to Claude Henault describes a Temperature Regulator
For A Catalytic Converter, in which air warmed by
passing through an engine coolant radiator, or ambient
air, is selectively passed through a shroud around a
catalytic converter in order to control the
temperature of the converter. While some form of
temperature regulation of a catalytic converter used
in the present invention could be incorporated, the
airflow provided by the cooling fan of the present
system is not for cooling the converter - filter, but
rather for cooling the outside of the converter
canister and surrounding shroud in order to reduce the
temperature of the shroud to a point no higher than
150 degrees Celsius.
U. S. Patent No. 3, 967, 929 issued on July 6, 1976 to
Tsuyoshi Tamazawa et al. describes an Exhaust Gas
Purifying System incorporating an air pump for
delivering additional air into the exhaust manifold
for further oxidation of unburned hydrocarbons and the
like, but further incorporating a selector valve for
routing the air through a catalytic converter
downstream from the exhaust manifold. The theory of
operation is that the excess air may be routed through
~ the catalytic converter for cooling the converter if
it gets too hot. However, the excess air would serve
to oxidize unburned hydrocarbons in the converter,
thus further increasing the heat output of the
converter. The air delivery system of the present
invention circulates around the outside of the
converter and filter, between the converter canister
and surrounding shroud, to cool the exterior of the
shroud below a predetermined level.
U. S. Patent No. 4,264,344 issued on April 28, 1981
to Otto A. Ludecke et al. describes a Diesel Engine
Exhaust Particulate Trap comprising two concentric
filter elements, unlike the axially disposed elements
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of the present system. At least the outer element of
the Ludecke et al. device is formed of material such
as pleated paper, which is totally unsuitable for use
with the heat developed by the catalytic converter -
5 filter element of the present invention. The present
invention serves to remove carbon particulates by
heating the catalytic converter - filter elements)
sufficiently highly by means of its reactions with
carbon monoxide and other exhaust pollutants, to break
down and oxidize such carbon particles as they pass
through the converter - filter.
U. S. Patent No. 4, 744, 217 issued on May 17, 1988 to
Dieter Goerlich et al. describes a Particle Separator
Arrangement In An Exhaust Pipe Of A Diesel Engine.
The device includes a particle trap with further means
for providing hot gases into the separator to burn out
the carbon particles trapped therein, from time to
time. The present invention does not include a
separate particulate trap, but rather makes use of the
combination filter and catalytic converters) used in
the system to trap such particulates. The converter
filter(s) operate at a sufficiently high temperature
to oxidize any unburned carbon particulates entering
the converter, and thereby continuously and
automatically clean the converter of particulates once
the converter warms to normal operating temperature.
The fan means used with the present invention does not
cool the converter core, but rather directs cooling
airflow around the outside of the converter - filter
canister and between the canister and shroud to cool
the exterior of the device to no more than a
predetermined maximum temperature.
U. S. Patent No. 5,105,619 issued on April 21, 1992
to Minoru Arai describes a Regeneration System For
Particulate Trap, wherein the heating means. for the
trap is an electric resistance heater. The present
system utilizes the existing catalytic converters)
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both to trap particulates as well as to oxidize those
trapped particulates by means of the heat generated in
the catalytic converter(s). Arai does not disclose a
catalytic converter, nor any air ducting around the
exterior of the trap, as is provided for cooling the
exterior housing of the present system.
U. S. Patent No. 5,243,819 issued on September 14,
1993 to Siegfried Woerner et al. describes an Exhaust
Gas Cleaning Device For Diesel Engines, similar to the
particulate separators or traps disclosed by Goerlich
et al. and Arai and discussed above. Woerner et al.
use a supplementary burner to heat the trap, rather
than providing a combination catalytic converter -
filter and using the heat of the catalytic reaction to
burn off the particulates, as is done in the present
invention. Moreover, Woerner et al. provide for the
routing of the supplemental burner gases around the
outside of the trap, in order to heat the relatively
cooler outer portions of the trap. The present
invention provides insulation around the catalytic
converter canister, which serves (1) to maintain the
heat of the converter for more efficient reaction, and
(2) to reduce the convected heat to below a
predetermined maximum level.
U. S. Patent No. 5,272,874 issued on December 28,
1993 to Norbert Paas describes an Exhaust Treatment
System for mine certified diesel engines, for reducing
exhaust emissions, particulates, and cooling the
exhaust, as required by regulations. However, Paas
goes about the solution to the problem in an entirely
different manner than that of the present invention,
using a considerably more complex apparatus which
requires intermittent cleaning and replacement of
certain elements. Paas provides a plurality of
relatively small catalytic converters at each exhaust
manifold tube, which small converters are inefficient
and difficult to heat to the desired temperature for
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optimum operation, particularly in view of the water
cooled exhaust manifold tubes immediately upstream of
each of the converters. The present invention
preferably utilizes a single combination catalytic
converter and filter, or alternatively a series of two
or more, rather than a plurality of such converters in
parallel, as does Paas. Also, while Paas states that
his catalytic converters serve to eliminate some of
the particulate matter from the exhaust, he must rely
upon a particulate filter downstream of the catalytic
converters in order to remove the balance of
particulate material, whereas the present system uses
the catalytic converters to remove essentially all of
the particulate material required to be removed from
the exhaust by regulation. No additional filters or
other elements are required in the present invention.
Paas then circulates the engine exhaust through a heat
exchanger in order to cool it sufficiently to pass
through a relatively inexpensive disposable filter.
However, the carbon buildup within the relatively cool
heat exchanger must be handled in some manner. Paas
responds to this problem by injecting water into the
system from time to time, which flashes to steam to
blow the carbon residue from the heat exchanger.
While the Paas system does allow a relatively
inexpensive, disposable exhaust particulate filter to
be used, the apparatus providing for such an
inexpensive filter is relatively complex and costly,
unlike the present system. Where Paas uses water to
cool his exhaust system, the present system is cooled
with air, with the cooling medium never entering the
exhaust system until the exhaust has been completely
processed, at the extreme output end of the system.
U. S. Patent No. 5,403,557 issued on April 4, 1995
to Harold L. Harris describes an Emission Control
Apparatus For Diesel Engine, including a particulate
trap and noise reduction device combined in a single
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unit. The particulate trap is upstream of a separate
catalytic converter, to remove substantially all of
the particulates from the exhaust gases before they
reach the converter, unlike the present invention
which utilizes the combination converter and filter to
remove particulates in addition to other undesirable
exhaust gases. While Harris also provides some sound
muffling means with his apparatus, he is silent
regarding any means of reducing the exterior
temperature of the device. The present system
includes external temperature reduction means,
comprising a fan for air flow between the insulated
catalytic converter canister and a surrounding shroud.
U. S. Patent No. 5,431,706 issued on July 11, 1995
to Norbert Paas describes a Disposable Particulate
Filter generally comprising a pair of concentric,
toroidally shaped filter elements. Exhaust passes
between the two elements, with filtered exhaust
passing either outwardly around the outermost element,
or centrally outward from the center of the inner
element. Paas notes that experiments wherein the
semi-permanent catalytic converter element has been
used to trap and oxidize the particulate material from
a diesel exhaust have not been successful when such
engines are used in light duty cycles (column 1, lines
62 - 68), but fails to consider insulating the
converter to retain heat and to reduce the temperature
of the outer shell, as is done in the present
invention.
Finally, U. S. Patent No. 5,488,826 issued on
February 6, 1996 to Norbert Paas describes a Heat
Isolated Catalytic Converter. This patent is a
continuation in part of Paas' earlier issued U. S.
Patent No. 5,272,874, and incorporates a similar
catalytic converter structure, with separate
converters housed in each exhaust manifold tube from
each exhaust port of the engine. However, the
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continuation patent provides for a pair of annular insulation
gaps or spaces concentric with each converter, to reduce heat
transfer to the exhaust manifold tubes. It would appear that
Paas recognized the shortcomings of the catalytic converter
structure of his earlier issued '874 patent, with the
relatively small converters in direct contact with the liquid
cooled exhaust manifold tubes and resulting inability of the
converters to attain sufficient temperature for suitable
operation and for achieving the stated purpose of oxidizing
some of the particulate matter of the diesel exhaust. However,
the plural, relatively small converters of the Pass '826 patent
are still considerably more difficult to heat to an optimum
operating temperature than the present single converter and
filter combination, or plural converters and filters in series,
of the present invention, and the liquid cooling provided by
Paas further lowers the temperature of adjacent structures to
a degree considerably less than that desired or permitted by
regulation.
None of the above inventions and patents, taken either
singly or in combination, is seen to describe the instant
invention as claimed.
SUI~IARY OF THE INVENTION
The present invention is a diesel exhaust conditioning
system. The system includes at least one combination catalytic
converter and particulate filter. A canister is included which
has a generally closed first end with an engine exhaust inlet
therethrough and an opposite open second end, for containing
the at least ore converter and filter therein. A shroud is
included with an open first end and an opposite open second
end, for installing about the canister. The shroud is larger
than the canister and defines an airflow path therebetween when
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the canister is installed within the shroud. A fan is secured
to the first end of the shroud, for blowing air between the
canister and the shroud, for cooling the shroud. A diffuser
is secured to the second end of the canister, for radially
deflecting exhaust gases exiting from the converter and filter
and the canister and mixing the exhaust gases with air within
10 the airflow path between the canister and the shroud. The
invention also includes a diesel exhaust conditioning system
in combination with a diesel engine.
In accordance with another embodiment of the present
invention there is provided a diesel engine and a diesel
exhaust conditioning system therefor, comprising in
combination: a diesel engine; a diesel exhaust conditioning
system including at least one combination catalytic converter
and particulate filter, a canister, a shroud, a fan, and a
diffuser; the canister having a generally closed first end with
an engine exhaust inlet therethrough and an opposite open
second end, for containing the at least one converter and
filter therein; the shroud having an open first end and an
opposite open second end, for installing about the canister,
with the shroud being larger than the canister and defining an
airflow path therebetween when the canister is installed with
the shroud; the fan being secured to the first end of the
shroud, for blowing air between the canister and the shroud,
for cooling the shroud; and the diffuser secured to the second
end of the canister, for radially deflecting exhaust gases
exiting from the converter and filter and the canister and
mixing the exhaust gases with air within the airflow path
between the canister and the shroud.
These and other features of the present invention will
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become readily apparent upon further review of the following
specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an exploded perspective view of the present
diesel exhaust conditioning system, showing its various
components and their relationship.
20
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Figure 2 is an elevation view in partial section of
the assembled diesel exhaust conditioning system,
showing various details thereof.
Similar reference characters denote corresponding
features consistently throughout the attached
drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention comprises a diesel exhaust
conditioning system which converts hazardous exhaust
gases such as oxides of nitrogen, carbon monoxide, and
unburned hydrocarbons to innocuous gases, and further
converts the solid hydrocarbon and carbon particulates
emitted by diesel engines, to innocuous gaseous form.
These multiple achievements are accomplished by means
of one or more catalytic converters, which also act as
a particulate trap (s) or filter (s) for the device. As
particulates enter the catalytic converter and filter
assembly, they are oxidized further by the heat
emitted from the catalytic reaction of the conversion
of other gaseous exhaust emissions, to be converted to
a gaseous state. The present catalytic converter
means is maintained at a sufficiently high temperature
to accomplish the above functions once it has been
thoroughly heated by normal operation.
At the same time, it is critical that the outer
surface of the assembly, and the exhaust gases
emanating from the device, be kept below a
predetermined maximum temperature. The present
invention also accomplishes this, in order to meet or
exceed regulations developed in various jurisdictions
for diesel engines used in enclosed environments, such
as the underground mining industry. As an example of
the above, Pennsylvania Article II-A Diesel Powered
Equipment Regulations have relatively strict limits as
to gaseous and particulate emissions, and also limit
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the exhaust temperature and external temperature of
the exhaust system, as described further above.
Figure 1 provides an exploded perspective view of
the present diesel exhaust conditioning system,
designated generally by the reference numeral 10
throughout the drawings. The system 10 includes at
least one catalytic converter 12 therein, which is
preferably a three way converter, capable of oxidizing
carbon monoxide and unburned hydrocarbons, as well as
reducing oxides of nitrogen to their component gases.
Other types of converters may be incorporated in the
present invention, if desired. Such converters are
conventional in the art and are known to be used with
both spark ignition and conventional compression
ignition (diesel) engines, such as the previously
known diesel engine disclosed in any of the U. S.
Patents to Paas and discussed further above,
incorporated herein by reference.
The converter 12 is capable of accepting relatively
high reaction temperatures, for oxidizing the solid
carbon and hydrocarbon particulates which are
typically emitted in diesel engine exhaust. The
converter 12 of the present invention may be formed of
coated ceramic materials to withstand the heat output
generated in the conversion of both gaseous and solid
particulates. Typically, diesel engine emissions
controls have incorporated a conventional catalytic
converter, in line with a particulate filter or trap
to capture the solid particulates from the diesel
exhaust. The present invention enables the catalytic
converter to act as the particulate filter
simultaneously in combination with its exhaust gas
conversion, by means of the relatively high
temperatures at which the converter - filter 12 is
maintained during operation.
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The combination catalytic converter and particulate
filter or trap 12 is removably installed within a
closely fitting canister 14 which surrounds the
converter - filter 12. The canister 14 is formed as
a relatively thick structure, with one or more layers
of insulation material l6 between the inner and outer
shells 18 and 20, as shown more clearly in the partial
section view of Figure 2. This insulation 16 within
the canister walls 18 and 20 serves to retain the heat
generated by the converter and filter 12 within the
canister 14 for more ef f icient operation, particularly
relating to oxidation of the hydrocarbon and carbon
diesel exhaust particles entering the converter -
filter 12. The insulation 16 also serves to reduce
heat conducted and radiated through the canister 14 by
the converter - filter 12, thus reducing the
temperature of the exterior wall or shell 20 of the
canister 14.
A spark/flame arrestor 22 may be installed in series
with the converter - filter 12, according to any
requirement therefor and depending upon the operating
environment of the system 10. The arrestor 22 is also
removably installed in the canister 14, with the first
or input end flange 24 of the spark arrestor 22
adjacent the second or output end flange 26 of the
converter - filter 12 (they may be separated by a
gasket 28, with an additional gasket 30 at the forward
or inlet end flange 32 of the converter-filter 12),
and the arrestor opposite second or output end flange
34 toward the corresponding canister second or output
end 32. The spark arrestor 22 may also incorporate an
additional catalytic converter, or converter - filter,
similar to the device 12 discussed further above.
A diffuser 36 is installed behind the second or
output end flange 34 of the spark arrestor 22, secured
to the second or output end 38 of the canister 14.
The diffuser 36 has a concentric, inwardly pointed
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conical projection 40, shown in Figure 2, which serves
to deflect exhaust gases flowing generally axially
from the second or output end of the spark arrestor
22, radially outwardly, as indicated by the exhaust
5 arrows E in Figure 2. The diffuser 36 includes a
plurality of peripheral, axial spacers 42, which serve
to separate the outer rim of the diffuser 36 from the
second end 38 of the canister 14, and define a radial
exhaust gas passage 44 therebetween, as shown in
10 Figure 2.
The canister 14 includes a plurality of longitudinal
ribs or ridges 46 formed along the inner surface 18 of
the canister 14. It will be noted that the various
flanges and gaskets 24 through 34 of the various
15 components housed within the canister 14, each have a
corresponding plurality of slots or grooves 48, as
shown in Figure 1. These peripheral slots 48 engage
and mate with the ribs 46 formed within the canister
14, to hold the converter - filter 12, spark arrestor
22, and gaskets 28 and 30 within the canister 14 and
prevent non-axial movement thereof relative to the
canister 14.
The spacer channels 42 of the diffuser 36 correspond
to and fit over each of the canister second ends of
the ribs 4 6 , and bear against the second end flange 34
of the spark arrestor 22 when the converter - filter
12, arrestor 22, and gaskets 28 and 30 are installed
within the canister 14, thereby precluding axial
movement of the components 12, 22, 28, and 30 within
the canister 14.
The ribs 46 each include an axial threaded fastener
passage 50 adjacent the second end 38 of the canister
14. A plurality of threaded fasteners 52 is used to
secure the diffuser 36 to the second or exhaust output
end 38 of the canister 14. Thus, the removable
securing of the diffuser 36 to the second end 38 of
the canister 14, by means of fasteners 52 engaging the
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passages 50 of the ribs 46, removably sandwiches the
converter - filter 12, spark arrestor 22, and gaskets
28 and 30 between the diffuser 36 and the essentially
closed first or exhaust inlet end 54 of the canister
14. (An exhaust inlet pipe or passage 56 is provided
in the first end 54 of the canister 14, preferably
laterally or radially disposed as shown in the
drawings.) A corresponding plurality of springs 58 is
provided between the heads of the fasteners 52 and the
diffuser 36, to allow for longitudinal thermal
expansion of the assembly comprising the converter -
filter 12, spark arrestor 22, gaskets 28 and 30, and
diffuser 36 within the canister 14.
The canister 14, with the above described components
installed therein, is surrounded by a heat deflecting
shroud 60. The shroud 60 has an open first or air
entrance end 62, and an opposite open second or
exhaust end 64. The inner cross sectional dimension
or diameter 66 of the shroud 60 is larger than the
outer cross sectional dimension or diameter 68 of the
canister 14, with the difference between the two
defining an airflow path 70 therebetween.
Air, indicated by the arrows A in Figure 2 , f lows in
a generally longitudinal or axial direction through
the airflow path, to mix with and cool the exhaust
gases E exiting from the canister 14, within the
second end 64 of the shroud 60, as indicated by the
mixed air and exhaust arrows AE. The air A is
delivered by a fan 72 installed in the inlet opening
62 of the shroud 60. Preferably, the fan 72 is an
axial fan, with the rotary axis of the fan disposed
concentrically with the longitudinal axis of the
remainder of the system 10, as shown in the drawing
figures. However, other types of fans (offset
"squirrel cage" blowers, etc.) may be used if so
desired, depending upon the available space and its
configuration for the present system 10.
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It will be seen that even with the canister
insulation 16 surrounding the converter and filter 12
installed therein, that the outer wall or surface 20
of the canister 14 will become quite hot during normal
operation. Typically, the converter and filter 12
will reach temperatures of over one thousand degrees
Fahrenheit, due to the catalytic reactions taking
place therein as exhaust products are converted to
harmless gases. Thus, the outer surface 20 of the
canister 14 will likely reach temperatures of at least
a few hundred degrees Fahrenheit, unless some cooling
means is provided. The fan 72 provides cooling
airflow A over the outside 20 of the canister 14, and
also serves to cool the shroud 60 from any effects of
radiated heat from the canister 14. The air A mixing
with the exhaust E also serves to cool the exhaust
temperature to levels acceptable according to
regulations.
The fan 72 shown in Figure 2 is mechanically
powered, by a conventional V-belt (not shown) which
turns a pulley 74, in turn driving the fan blades 76.
The belt may be powered by the accessory drive of the
diesel engine with which the system 10 is used. Thus,
whenever the engine is running, the fan blades 76 are
spinning to draw air A through the airflow path 70
between the canister 14 and shroud 60. Other means of
powering the fan 72 may be provided as desired. For
example, a conventional electric motor (not shown) may
be used to power the fan 72, with a switch wired in
parallel with an electric fuel pump for the engine, or
some other electrical circuit which is activated
simultaneously with the engine. An electrically
powered fan might be advantageous in that electrical
power to the fan could be controlled by a thermostat
or temperature probe within the canister 14 or air
flow passage 70, with the fan continuing to run and
delivering cooling air through the shroud 60 after the
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engine is stopped. Another means of powering the fan
might be to use the energy provided by the engine
exhaust to turn an impeller which could be used to
drive the fan, somewhat along the lines of a
conventional exhaust driven turbosupercharger.
The shroud 60 shown in Figures 1 and 2 is formed of
two pieces of relatively thin sheet material, each
comprising a generally semicylindrical shroud half.
The two shroud 60 components each include mating
longitudinal flanges 78 (Figure 1), which are secured
to one another by screws 80 (Figure 2). An engine
exhaust inlet passage 82 is formed in each shroud 60
half, to fit around the exhaust inlet pipe 56.
The shroud 60 assembly is spaced apart from the
canister 14 contained therein by a plurality of
internal supports 82, as shown in Figure 1. The
supports 82 may comprise continuous lengths each
having a T-cross section, with the crossmember of the
T providing a relatively wide surface upon which the
outer surface 20 of the canister 14 rests.
Alternatively, a series of inwardly directed rods each
having a support button thereon, might be used to
space the shroud 60 away from the canister 14. Other
means (springs, etc.) might also be used, as desired.
The present diesel engine exhaust conditioning
system 10 may also be constructed as an explosion
proof unit, if so desired, with relatively little
modification. Such explosion proof construction is
very important in various environments, such as the
underground mining industry, where potentially
explosive gases and dust are frequently found. An
alternative shroud 84, formed of a single piece of
relatively thick metal, may be used to house the
canister 14, fan 72, and other components within the
canister 14. Rather than assembling the shroud 60
laterally around the canister 14 and its components,
the canister 14 is installed within the single piece
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shroud 84 by insertion into the first end 86 thereof.
A second spark arrestor (not shown) may be installed
between the canister 14 and the fan 72, with the fan
72 being installed to the first end 86 of the shroud
84 to complete the assembly. Other details as
required by regulation and practice, such as welding
the engine exhaust inlet pipe to the system to provide
a leakproof seal, may be used as necessary.
It will be noted that the various components
comprising the present exhaust conditioning system 10,
i. e., the converter and filter 12, canister 14, spark
arrestor 22, diffuser 36, assembled shroud 60 or
single piece shroud 84, and fan 72, each have a
cylindrical or round cross sectional shape, as shown
in the drawing figures. The converter - filter 12
(and spark arrestor 22, if used) fit concentrically
within the canister 14, with the preferably axial fan
72 fitting closely and concentrically within the first
or inlet end 62 of the shroud 60 (or inlet end 86 of
the single piece shroud 84), with the shroud 60 or 84
in turn fitting concentrically about the canister 14
and diffuser 36. However, the various components
comprising the present diesel exhaust conditioning
system 10 may be formed to have other geometric cross
sectional shapes (oval, elliptical, rectangular, etc.,
as desired, depending upon the space or area in which
the device is to be installed, and other
considerations.
In summary, the present diesel engine exhaust
conditioning system will be seen to provide a
significant advance over systems of the prior art,
used in the underground mining industry and other
enclosed environments. The use of a catalytic
converter operating at a relatively high temperature
in order to convert noxious gases to innocuous
products, and also to convert solid particulates to
innocuous gases, eliminates the need for an additional
CA 02220210 2001-02-26
particulate filter in the device. The catalytic converter and
filter combination may be maintained at the desired temperature
for accomplishing both of the above functions, by means of a
durable, high temperature insulation (such as ceramic material,
glass fiber, etc.) in the canister surrounding the converter
and filter. Yet, both the outer temperature and exhaust
10 temperature of the device are maintained within the limits
required by regulation, by means of an outer shroud spaced
apart from the insulated canister, and a fan blowing ambient
air between the canister and shroud. The air passing between
the canister and shroud is mixed with the relatively hot
exhaust as it leaves the canister by means of a diffuser, thus
lowering the exhaust gas temperature to a suitable level. The
system is relatively durable and maintenance free, in
comparison to sys;~ems requiring periodic coolant replenishment
or filter cleaning or replacement. Yet, the device may be
20 easily serviced as required, due to the bolt-in installation
of the various components within the canister and the ease of
removal of the shroud from the canister when required. The
present exhaust conditioning system will serve well the
underground mining industry and other fields requiring diesel
engine power in enclosed environments, and may be readily
adapted for use with other stationary or vehicular diesel
engines with little or no modification.
The preferred embodiments of the invention provide an
s0 improved diesel exhaust conditioning system for the reduction
of gases and particulate emissions and exhaust temperature from
a diesel internal combustion engine. The system is
particularly structured for use with diesel engines in the
underground mining environment and other enclosed areas of
operation, and may be structured for use with other types of
CA 02220210 2001-02-26
20a
internal combustion engines and in other operating
environments. The system utilizes catalytic converter means
for reducing noxious and toxic gaseous exhaust emissions from
a diesel engine, with the catalytic converter means also
serving as filter means for reducing particulate exhaust
emissions from the engine as well. The system includes air
li> cooling means for reducing the temperature of the system and
exhaust. In at least one embodiment, the system is structured
as an explosion proof device for use in enclosed areas
potentially containing explosive gases, dust, and the like.
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.
2 (J
JO
