Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02595155 2007-07-27
SECURING CATALYST ELEMENT IN CATALYTIC CONVERTER WITH
BOLTED BAR
FIELD OF THE INVENTION
[001] The present invention relates generally to catalytic converters, and
particularly to methods and devices for securing a catalytic element in a
catalytic
converter.
BACKGROUND OF THE INVENTION
[002] A catalytic converter is a device that catalyzes chemical reactions
in
which a combustion by-product or emission substance (such as CO, NOR, or the
like) is converted to a more environmentally-friendly or less undesirable
substance
(such as CO2, H20, N2, or the like). Catalytic converters are commonly used
for
emission control by providing a catalyst environment (typically without
consumable chemicals) to treat exhaust gases from, e.g., internal combustion
engines, air conditioning systems, or the like. Typically, a catalytic
converter
includes a disk or block-shaped catalyst element mounted in a housing, and is
placed in the exhaust path of an emission producing system or machine. It is
desirable that the catalyst element is readily replaceable. It is also
desirable to
form a leak-proof seal between the catalyst element and the housing wall so
that
all the exhaust gas will go through the catalyst element to maximize
conversion.
In conventional catalytic converters, different fixture assemblies have been
used
to secure the catalyst element in position. However, these fixture assemblies
suffer some drawbacks. For instance, in conventional catalytic converters, one
cannot conveniently adjust the pressure applied to the catalyst element for
securing it in position and forming a tight seal. Some of them do not apply
sufficient pressure to form a stable tight seal; others have complicated
structures
and are inconvenient to use. They are also not adjustable to accommodate
catalyst element size variations. In some conventional catalytic converters,
the
seal between the catalyst core and the housing is tight but catalyst core is
fixedly
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mounted in the housing and therefore is not removable for maintenance or
replacement.
[003] Accordingly, there is a need for a catalytic converter that overcomes
one or more of these shortcomings.
SUMMARY OF THE INVENTION
[004] In accordance with one aspect of the present invention, there is
provided a catalytic converter comprising a housing defining a conduit and
having
a support wall defining an opening in the conduit; a removable catalyst
element
covering the opening for treating an exhaust gas passing through the conduit,
a
first side of the catalyst element abutting a surface of the support wall
adjacent to
the periphery of the opening; a removable bar abutting a second, opposite side
of
the catalyst element; an anchorage anchoring a first end of the bar to the
wall; and
a bolt bolting a second end of the bar to the wall with a threaded engagement
to
press the catalyst element against the surface of the wall, thus clamping the
catalyst element between the wall and the bar, wherein the bolt and threaded
engagement are configured such that when the threaded engagement is
tightened, the clamping force applied by the bar to press the catalyst element
against the wall is increased, wherein the bar, wall, anchorage and bolt are
formed from respective materials having different thermal expansion
coefficients,
the materials selected so that the clamping force increases with increasing
temperature, and the clamping force is sufficiently strong at an elevated
operating
temperature that the catalyst element sealingly engages the wall, to prevent
leakage of the gas through a gap between the surface of the wall and the
catalyst
element. The first end of the bar may be removably anchored to the wall. The
anchorage may be mounted in the housing, and may have an aperture
releaseably receiving and engaging the first end of the bar thus anchoring the
first
end. The anchorage may include an elongated arm extending from the wall, the
arm having two joined plate members forming a generally L-shaped cross-
section,
one of the plate members facing the catalyst element and having the aperture.
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The first end of the bar may have a pin, the pin slidably received in the
aperture of
the anchor support. The bar may have two opposite edges, one of the edges
abutting the catalyst element, the pin extending along a line between, and
generally parallel, to the edges, the line being closer to one of the edges.
The bar
may have a recessed portion between the ends, the recessed portion being
spaced from the catalyst element to allow passage of the gas. The bar may have
a central portion protruding from the recessed portion towards the catalyst
element for restricting expansion of a central portion of the catalyst
element. The
second end of the bar may have a sleeve, the bolt extending through the
sleeve.
The catalytic converter may include a nut and a support plate, the support
plate
forming the wall and having an aperture, the bolt extending through the
aperture
and being coupled to the nut such that the bolt and the nut clamp the plate
and
the bar therebetween. The catalytic converter may include a washer-gasket unit
placed between the nut and the support plate. The catalytic converter may
include a restriction bar mounted in the housing and across the opening of the
wall, for restricting expansion of a central portion of the catalyst element.
The
catalyst element may include a peripheral frame and a catalyst core mounted to
the frame, the frame bearing the clamping force applied to the catalyst
element by
the bar and the wall. The frame may be formed from a material selected from
carbon steel and stainless steel. The wall and the bar may have a first
thermal
expansion coefficient, and the bolt and the anchorage may have a second
thermal
expansion coefficient smaller than the first thermal expansion coefficient.
The first
thermal expansion coefficient may be about 9.6 x 10-6 in/in. F, and the second
thermal expansion coefficient may be about 7.6 x 10-6 in/in. F. Each one of
the
wall and the bar may be made of stainless steel, and each one of the bolt and
the
anchorage may be made of carbon steel. The bar may be a first bar, and the
catalytic converter may include a second bar having a first end anchored to
the
wall and a second end bolted to the wall thus clamping the catalyst element
between the wall and the second bar. Each one of the first bar and second bar
may have a longitudinal axis, the longitudinal axes being aligned with each
other
at an angle from 30 to 90 degrees. A central portion of each one of the first
and
second bars may have a notch, the notches facing each other and being sized to
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allow the second bar to be positioned across the first bar. The catalytic
converter
may include a plurality of catalyst elements. The support wall may be an inlet
wall
and the opening of the support wall may be an inlet opening, the housing may
have an outlet wall defining an outlet opening, and another catalyst element
covering the outlet opening may be clamped between the outlet wall and a
pressure bar bolted to the outlet wall. The catalytic converter may include a
flow
distributor mounted in the housing upstream of the opening of the wall for
distributing the gas over the opening, the flow distributor comprising a cone-
shaped tube. The flow distributor may include a plurality of nested, cone-
shaped
tubes.
[005] In
accordance with another aspect of the present invention, there is
provided a catalytic converter comprising a housing defining a conduit and
having
support means for defining an opening in the conduit; a removable catalyst
element covering the opening for treating an exhaust gas passing through the
conduit, a first side of the catalyst element abutting a surface of the
support
means adjacent to the periphery of the opening; pressure means for abutting a
second, opposite side of the catalyst element; anchorage means for anchoring a
first end of the pressure means to the housing; and bolt means for bolting a
second end of the pressure means to the support means, with a threaded
engagement means to press the catalyst element against the surface of the
support means, thus clamping the catalyst element between the support means
and the pressure means, wherein the bolt meanings and threaded engagement
means are configured such that when the threaded engagement means is
tightened, the clamping force applied by the pressure means to press the
catalyst
element against the support means is increased, wherein the pressure means,
support means, anchorage means and bolt means are formed from respective
materials having different thermal expansion coefficients, the materials
selected
so that the clamping force increases with increasing temperature, and the
clamping force is sufficiently strong at an elevated operating temperature
that the
catalyst element sealingly engages the support means, to prevent leakage of
the
gas through a gap between the surface of the support means and the catalyst
element.
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[006] In accordance with a further aspect of the present invention, there
is
provided a method of securing a catalyst element in a catalytic converter,
comprising providing a housing defining a conduit and having a support wall
defining an opening in the conduit; covering the opening with a removable
catalyst
element for treating an exhaust gas passing through the conduit, a first side
of the
catalyst element abutting a surface of the wall adjacent to the periphery of
the
opening; and abutting a second, opposite side of the catalyst element with a
pressure bar by anchoring a first end of the bar to the wall with an anchorage
and
bolting a second end of the bar to the wall with a bolt and a threaded
engagement
to press the catalyst element against the surface of the wall, thus clamping
the
catalyst element between the wall and the bar, wherein the bolt and threaded
engagement are configured such that when the threaded engagement is
tightened, the clamping force applied by the bar to press the catalyst element
against the wall is increased, wherein the bar, wall, anchorage and bolt are
formed from respective materials having different thermal expansion
coefficients,
the materials selected so that the clamping force increases with increasing
temperature, and the clamping force is sufficiently strong at an elevated
operating
temperature that the catalyst element sealingly engages the wall, to prevent
leakage of the gas through a gap between the surface of the wall and the
catalyst
element.
[007] In accordance with a further aspect of the present invention, there
is
provided a catalytic converter comprising a housing defining a generally
longitudinally oriented conduit extending between an inlet and an outlet, the
housing having a generally transversely oriented support wall mounted in the
conduit between the inlet and the outlet, the support wall having an opening
permitting an exhaust gas to pass through the conduit; a removable catalyst
element covering the opening in the support wall for treating the exhaust gas
passing through the conduit; the catalyst element having a front side facing
the
support wall and a rear opposite side; and at least one member abutting and
extending across the rear side of the catalyst element, the member having a
first
end pivotally connected to the housing and a second opposite end of the member
connected with a bolt to the support wall wherein in use, the catalyst element
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held in compression between the support wall and the member. The bolt may be
adjustable to vary the compression of the catalyst element as it is held
between
the support wall and the member. The second end of the member may be
adapted to releasably engage the housing. The second end of the member may
have a pin receivable in an aperture in the housing. The housing may include a
longitudinally extending arm member and wherein the aperture is in the arm
member.
[008] An exemplary embodiment is a catalytic converter that has a
housing defining a conduit and having a support wall defining an opening in
the
conduit; a removable catalyst element covering the opening for treating an
exhaust gas passing through the conduit, and a removable bar abutting the
catalyst element, a first end of the bar anchored to the wall and a second end
of
the bar bolted to the wall thus clamping the catalyst element between the wall
and
the bar. The first end of the bar may be removably anchored to the wall. The
catalytic converter may have an anchorage mounted in the housing, the
anchorage having an aperture releaseably receiving and engaging the first end
of
the bar thus anchoring the first end. The anchorage may include an elongated
arm extending from the wall, the arm having two joined plate members forming a
generally L-shaped cross-section, one of the plate members facing the catalyst
element and having the aperture. The first end of the bar may have a pin, the
pin
slidably received in the aperture of the anchor support. The bar may have two
opposite edges, one of the edges abutting the catalyst element, the pin
extending
along a line between, and generally parallel, to the edges, the line being
closer to
one of the edges. The bar may have a recessed portion between the ends, the
recessed portion being spaced from the catalyst element to allow passage of
the
gas. The bar may have a central portion protruding from the recessed portion
towards the catalyst element for restricting expansion of a central portion of
the
catalyst element. The catalytic converter may include a bolt that bolts the
second
end of the bar to the wall, the second end of the bar having a sleeve, the
bolt
extending through the sleeve. The catalytic converter may include a nut and a
support plate, the support plate forming the wall and having an aperture, the
bolt
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extending through the aperture and being coupled to the nut such that the bolt
and
the nut clamp the plate and the bar therebetween. The catalytic converter may
include a washer-gasket unit placed between the nut and the support plate. The
catalytic converter may have another bar having a first end anchored to the
wall
and a second end bolted to the wall thus clamping the catalyst element between
the wall and the second bar. Each one of the first bar and second bar may have
a
longitudinal axis, which may be aligned with each other at an angle from 30 to
90
degrees. A central portion of each one of the first and second bars may have a
notch, the notches facing each other and being sized to allow the second bar
to
be positioned across the first bar. The catalytic converter may include a
restriction
bar mounted in the housing and across the opening of the wall, for restricting
expansion of a central portion of the catalyst element. The catalyst element
may
include a peripheral frame and a catalyst core mounted to the frame, the frame
bearing the clamping force applied to the catalyst element by the bar and the
wall.
The frame may be formed from a material selected from carbon steel and
stainless steel. The bar may be anchored and bolted to the wall with an
anchorage and a bolt, the bar, wall, anchorage and bolt being formed from
respective materials having different thermal expansion coefficients, the
materials
selected so that the clamping force applied to the catalyst element by the bar
and
the wall increases with increasing temperature. The clamping force may be
sufficiently strong at an elevated operating temperature that the catalyst
element
sealingly engages the wall, to prevent leakage of the gas through a gap
between
the wall and the catalyst element. The wall, the bar and the catalyst element
may
have a first thermal expansion coefficient, and the bolt and the anchorage may
have a second thermal expansion coefficient smaller than the first thermal
expansion coefficient. The first thermal expansion coefficient may be about
9.6 x
10-6 in/in. F, and the second thermal expansion coefficient may be about 7.6 x
10-
6 in/in. F. Each one of the wall and the bar may be made of stainless steel,
and
each one of the bolt and the anchorage may be made of carbon steel. The
catalytic converter may comprise a plurality of catalyst elements. The support
wall
may be an inlet wall and the opening of the support wall may be an inlet
opening.
The housing may also have an outlet wall defining an outlet opening. Another
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catalyst element covering the outlet opening may be clamped between the outlet
wall and a pressure bar bolted to the outlet wall. The catalyst elements may
be
independently mounted to the inlet and outlet walls. The catalytic converter
may
include a flow distributor mounted in the housing upstream of the opening of
the
wall for distributing the gas over the opening, the flow distributor
comprising a
cone-shaped tube. The flow distributor may include a plurality of nested, cone-
shaped tubes.
[008a] Another exemplary embodiment is a catalytic converter that
comprises a housing defining a conduit and having support means defining an
opening in the conduit; a removable catalyst element covering the opening for
treating an exhaust gas passing through the conduit, and pressure means
abutting the catalyst element, the pressure means bolted to the wall thus
clamping
the catalyst element between the wall and the pressure means.
[008b] Another exemplary embodiment is a method of securing a catalyst
element in a catalytic converter. A housing is provided which defines a
conduit
and has a support wall defining an opening in the conduit. The opening is
covered with a removable catalyst element for treating an exhaust gas passing
through the conduit. The catalyst element is abutted with a pressure bar by
anchoring a first end of the bar to the wall and bolting a second end of the
bar to
the wall, thus clamping the catalyst element between the wall and the bar.
[008c] Another exemplary embodiment is a catalytic converter comprising a
housing defining a generally longitudinally oriented conduit extending between
an
inlet and an outlet, the housing having a generally transversely oriented
support
wall mounted in the conduit between the inlet and the outlet, the support wall
having an opening permitting an exhaust gas to pass through the conduit; a
removable catalyst element covering the opening in the support wall for
treating
the exhaust gas passing through the conduit; the catalyst element having a
front
side facing the support wall and a rear opposite side; and at least one member
abutting and extending across the rear side of the catalyst element, the
member
having a first end pivotally connected to the housing and a second opposite
end of
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the member connected with a bolt to the support wall wherein in use, the
catalyst
element is held in compression between the support wall and the member. The
bolt may be adjustable to vary the compression of the catalyst element as it
is
held between the support wall and the member. The second end of the member
may be adapted to releasably engage the housing. The second end of the
member may have a pin receivable in an aperture in the housing. The housing
may include a longitudinally extending arm member and wherein the aperture is
in
the arm member.
[008d] Other aspects and features of the present invention will become
apparent to those of ordinary skill in the art upon review of the following
description of specific embodiments of the invention in conjunction with the
accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[009] In the figures, which illustrate, by way of example only,
embodiments
of the present invention,
[0010] FIG. 1 is an isometric perspective view of a housing of a catalytic
converter, for housing a disk-shaped catalyst element;
[0011] FIG. 2 is a side elevation view of the housing of FIG. 1;
[0012] FIG. 3 is a front elevation view of the housing of FIG. 1;
[0013] FIG. 4 a top plan view of the housing of FIG. 1;
[0014] FIG. 5 is a cutaway perspective view of a portion of the housing of
FIG. 1;
[0015] FIG. 6 is a rear perspective view of the portion of FIG. 5;
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[0016] FIG. 7 is a front elevation view of the portion of FIG. 5;
[0017] FIG. 8 is a cross-sectional view of the portion of FIG. 5, taken
along
the line 8-8;
[0018] FIG. 9 is an exploded view of the parts shown in FIG. 8;
[0019] FIG. 10 is a perspective view of the front plate shown in FIG. 6;
[0020] FIG. 11 is an elevation view of an anchoring arm;
[0021] FIG. 12 is a top plan view of the anchoring arm of FIG. 11;
[0022] FIG. 13 is an elevation view of a pressure bar;
[0023] FIG. 14 is a left elevation view of the pressure bar of FIG. 13;
[0024] FIG. 15 is a top perspective view of a first catalytic converter,
without
the pressure bars and the cover;
[0025] FIG. 16 is a side exploded perspective view of the catalytic
converter
of FIG. 15;
[0026] FIG. 17 is a top perspective view of the catalytic converter of
FIG.
15, without the cover;
[0027] FIG. 18 is a side perspective view of the catalytic converter of
FIG.
15;
[0028] FIG. 19 is a partially see-through and partially exploded
perspective
view of a second catalytic converter;
[0029] FIG. 20 is an elevation view of the catalytic converter of FIG.
19;
[0030] FIG. 21 is a right elevation view of the catalytic converter of
FIG. 20;
[0031] FIG. 22 is an elevation view of a variation of the catalytic
converter
of FIG. 21;
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[0032] FIG. 23 is a partially see-through elevation view of a third
catalytic
converter;
[0033] FIG. 24 is a left elevation view of the catalytic converter of
FIG. 23;
[0034] FIG. 25 is a partially see-through elevation view of a fourth
catalytic
converter;
[0035] FIG. 26 is a left elevation view the catalytic converter of FIG.
25;
[0036] FIG. 27 is a perspective view of another housing, for housing a
rectangular catalyst element arrangement; and
[0037] FIG. 28 is a cutaway view of a portion of the housing of FIG. 27.
DETAILED DESCRIPTION
[0038] In overview, it is discovered that catalyst elements can be
conveniently secured in position using pressure bars that may abut the
catalyst
element against the converter housing wall and may be bolted to the housing
wall
so that the pressure bars and the housing wall clamp the catalyst element
therebetween. The applied clamping force or pressure can be conveniently
adjusted to form a stable and suitable seal between the catalyst element and
the
wall. The catalyst element can also be installed or removed conveniently.
[0039] FIGS. 1 to 9 illustrate a housing 100 for a catalytic converter
(not
shown in entirety but see FIGS. 15 to 26), exemplary of an embodiment of the
present invention. Housing 100 houses a catalyst element 102 (shown in FIGS. 5
to 7). Housing 100 has a main flow chamber 104 and an access channel 106
extending laterally from flow chamber 104. Flow chamber 104 defines a fluid
conduit for an exhaust gas to flow through. The exhaust gas may be emitted
from
an engine or like emission-producing machines or systems.
[0040] Catalyst element 102 may be adapted for treating the exhaust gas.
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Catalyst element 102 may facilitate chemical reaction in exhaust gas that
passes
through it and may convert certain exhaust pollutants into environmental-
friendly,
such as less toxic or harmful, substances. Catalyst element 102 can be
inserted
into or removed from flow chamber 104 through access channel 106. A
removable cover 108 is secured on the outer end of access channel 106 for
closing housing 100. A sealing ring or gasket (not shown) may be typically
placed
between the outer end (flange) of access channel 106 and (flange) cover 108 to
provide leak-proof seal. Housing 100 may be placed in the exhaust path of an
emission-producing machine, such as an engine, so that exhaust gas is forced
to
go through catalyst element 102, as will be further described below.
[0041] Housing 100 includes a front plate 110 and a rear plate 112. Front
plate 110 defines an opening 114 around a central axis 116 and rear plate 112
defines an opening 118, for allowing the exhaust gas to go through flow
chamber
104 and catalyst element 102. As depicted, openings 114, 118 have a circular
profile, which matches the circular end face of catalyst element 102. Either
front
plate 110 or rear plate 112 may be placed upstream and the other downstream.
For illustration purposes, it is assumed herein that front plate 110 is
upstream and
opening 114 serves as the flow inlet while opening 118 is downstream and
serves
as the outlet. Thus, housing 100 defines a generally longitudinally oriented
fluid
conduit between inlet opening 114 and outlet opening 118. Front and rear
plates
110, 112 may be generally transversely oriented. A restriction bar 120 is
mounted
on housing 100 across opening 114, the use of which will become clear below.
As depicted, bar 120 may have a loop portion 121 that can expand when opening
118 becomes enlarged due to thermal expansion of plate 110 at elevated
temperatures.
[0042] As individually shown in FIG. 10, front plate 110 also has two
bore
holes 122, 124. Plate 110 has a collar 126 around opening 114 for positioning
and supporting catalyst element 102. Collar 126 supports and restricts lateral
movement of catalyst element 102 relative to axis 116. Collar 126 may have a
width selected to provide adequate support for catalyst element 102. As
depicted,
collar 126 may have a wider bottom portion and a narrower top portion, which
can
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conveniently provide both good support and easy access, as will become clear
below.
[0043] Plate 110 may have any suitable size depending on the application.
Plate 110 should be thick enough to support catalyst element 102 under
operating
conditions. It is desirable that plate 110 is not warped during fabrication.
Wall
182 may provide a generally flat surface for adequate seal. In one embodiment,
plate 110 may have a thickness of 1/4 in. The wider portion of Collar 126 may
have a width of about 3 in.
[0044] Plate 112 may be identical to plate 110, thus each of plates 110
and
112 may provide a support wall (one as an inlet wall and the other as an
outlet
wall) for supporting a respective catalyst element. The catalyst elements may
be
independently mounted to plates 110 and 112.
[0045] A fixture assembly 128 is provided for securing catalyst element
in
position. Fixture assembly 128, as better shown in FIGS. 5 to 9, may include
anchoring arms 130A, 130B (also individually and collectively referred to as
130),
pressure bars 132A, 132B (also individually and collectively referred to as
132),
bolts 134A, 134B (also individually and collectively referred to as bolts
134), nuts
136A, 136B (also individually and collectively referred to as 136), and washer-
gasket units 186 (also individually referred to as 186).
[0046] Anchoring arm 130 is individually shown in FIGS. 11 and 12. As
depicted, each anchoring arm 130 may be formed of two joined plate members
138 and 140, or from angle iron. Plate members 138 and 140 may be joined to
form a generally L-shaped support (angle iron). As can be appreciated, an L-
shaped support can provide stable support (higher allowable bending stress)
with
less material. As depicted plate member 138 may have two spaced apart
apertures 142. Arm 130 may be mounted on housing 100 such that it extends
generally longitudinally from plate 110 with plate member 138 facing opening
114
or catalyst element 102 when it rests on collar 126. Each arm 130 is used to
anchor an end of a pressure bar 132 which is generally transversely mounted.
Arms 130 may be fixedly mounted on plate 110, such as being welded to plate
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110. As depicted, arms 130 may be mounted to both plates 110 and 112, thus
forming beams extending between the two plates. Alternatively, in some
embodiments, the arms attached to each plate may be disconnected from the
other plate.
[0047] The size of arm 130 may vary depending on the application. In one
embodiment, plate members 138, 140 may have a thickness of 3/16 in to 1/4 in,
a
length of 13 in, and respective width of 1 in x 1-1/4 in. Arm 130 should be
strong
enough to stably anchor pressure bar 132 under operating conditions. For
example, arm 130 may be made from carbon steel, or similar materials.
[0048] Pressure bar 132 is individually shown in FIGS. 13 and 14.
Pressure bar 132 has end portions 144, 146, recessed portions 148 between the
end portions, and a central portion 150. One edge 152 of central portion 150
protrudes laterally from the edges 154 of recessed portions 148 such that edge
152 and edges 156, 158 at end portions 144 and 146 longitudinally align with
each other. The opposite edge 160 of central portion 150 is recessed laterally
from the edges 162 of recessed portions 148, thus forming a notch 164. The
edges 166, 167 of end portions 144, 146 align with each other. As can be
appreciated and better seen in FIGS. 1 and 6, notch 164 allows two pressure
bars
132 be cross-aligned and pressured against the same catalyst element 102.
[0049] A pin 168 may extend longitudinally from end portion 144 in a line
170 that may be offset from the central axis 172 which is parallel and at a
equal
distance from edges 166 and 167. As depicted pin 168 has a circular cross-
section. In other embodiments, pin 168 may have a different cross-section,
such
as oval, square, or the like. Pin 168 is sized so that it can be slidably
inserted into
and releaseably engage aperture 142, such that end portion of 144 of pressure
bar 132 is removably anchored relative to plate 110 and is pivotally connected
to
housing 100. Allowing pin 168 to slide and swing or pivot about when received
in
aperture 142 of arm 130 makes it easier to align end portion 146 of pressure
bar
132 into position.
[0050] End portion 146 of pressure bar 132 has a sleeve 174 for receiving
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the shank 176 of a bolt 134. Sleeve 174 is small enough so that the head 178
of
bolt 134 will not pass through.
[0051] The dimensions of pressure bar 132 may vary and can be readily
selected by persons skilled in the art depending on the application. In one
embodiment, pressure bar 132 may be made of stainless steel or similar
materials, and may have a length of about 27-13/16 in and a width of about 2-
9/16
in. Pin 168 may be a rod with a length of about 2 in and a diameter of about
0.5
in. Sleeve 174 and recessed portions 148 may have a width of about 3A in.
Pressure Bar 132 may have a thickness in the range of 3/16 in to 3/8 in.
[0052] In one embodiment, bars 132A and 132B may have identical sizes
and shapes. In another embodiment, bars 132A and 132B may have similar
general shapes but sized differently so that when they are "flipped" or
reversed in
position, the distance from pins 168 to wall 182 is slightly different.
[0053] Any suitable type of bolt and nut combination may be used for
bolting bars 132 to plate 110. Bolt 134 and nut 136 may have any suitable
shape,
size and threading. The material of bolt 134, however, should be selected with
care so that it is strong enough to withstand the applied force under the
normal
operating conditions and has a desired thermal expansion coefficient, as will
be
discussed below.
[0054] In one embodiment, bolt 134 may be made of carbon steel or similar
materials, and may have a length of about 6 in, and shank 176 of bolt 134 may
have a diameter of about 1/2 in. Nut 136 and threaded end 179 of bolt 134 have
matching sizes and threads for proper engagement.
[0055] As better shown in FIGS. 8 and 9, when installed, the front face
180
of catalyst element 102 abuts a rear wall 182 of plate 110. Pressure bar 132
is
positioned across and abuts portions of the rear face 184 of catalyst element
102.
End portion 144 of bar 132 is anchored to plate 110 as pin 168 is received in
aperture 142 of arm 130 which restricts the movement of end portion 144. End
portion 146 is bolted to plate 110 using bolt 134 and nut 136 so that pressure
bar
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132 and plate 110 clamp catalyst element 102 therebetween. A washer-gasket
unit 186 may be placed between plate 110 and nut 136, with the gasket side
facing plate 110 and the washer side facing nut 136, to prevent leakage of
exhaust gas through bore holes 122, 124.
[0056] The locations of arms 130 and bore holes 122 may be selected so
that when installed, longitudinal axes 172 of pressure bars 132A and 132B are
aligned with each other at an angle from 30 to 90 degrees. In one embodiment,
longitudinal axes 172 may be aligned at about 90 degrees.
[0057] Typically, catalyst element 102 has an outer rim frame 188 and an
inner catalyst core 190 attached to frame 188. Frame 188 is made of a rigid
and
strong material such as stainless steel. Inner core 190 may have a substrate
and
the suitable catalyst material is coated thereon. For example, the catalyst
material
may be effective for converting CO to CO2. Frame 188 protects core 190 and is
typically of substantially the same width as core 190, so that when catalyst
element 102 abuts plate 110, the abutting pressure is mainly born by frame
188.
[0058] As can be understood, as frame 188 of catalyst element 102 is of
substantially the same width as inner core 190, after initial installation
pressure
bars 132 contact catalyst element 102 at four contact points on frame 188.
Thus,
clamping pressures are applied to catalyst element 102 through frame 188.
[0059] FIGS. 8 and 9 showed only one pressure bar 132 with its notch 164
facing away from catalyst element 102, which corresponds to pressure bar 132A.
The other pressure bar, pressure bar 132B, is installed with its notch facing
pressure bar 132A and catalyst element 102. Due to the interfacing notches,
both
pressure bars 130A and 132B abuts frame 188 of catalyst element 102, at four
different contact points. With four contact points, axial movement of catalyst
element 102 is effectively and securely restricted. While a single pressure
bar
132 may be used in some embodiments, with two pressure points, the pressure
applied to the catalyst element (frame 188) is less evenly distributed and gas
may
leak between frame 188 and plate 110 during operation in some situations.
12
CA 02595155 2007-07-27
[0060] When bolt 134 and nut 136 are sufficiently tightened, a sufficient
force is exerted on catalyst element 102 so that catalyst element 102 is held
in
compression between plate 110 and pressure bar 132 and sealingly engages wall
182 of plate 110. The clamping force, and thus the compression of catalyst
element 102, can be easily adjusted by rotating nut 136 relative to bolt 134,
or
vice versa.
[0061] The longitudinal position of aperture 142 may be selected so that
the
pressure applied to frame 188 at the top proximate bolt 134 by end portion 146
of
pressure bar 132 is substantially the same as the pressure exerted at the
bottom
of frame 188 proximate arm 130 by end portion 144 of pressure bar 132.
[0062] In one embodiment, the materials for plate 110, arm 130, bar 132,
bolt 134 may be selected such that, for a given catalyst element 102, the
thermal
expansion coefficients of these parts are such that the force exerted on
catalyst
element 102 by plate 110 and bar 132 is higher at a higher temperature. Thus,
even when bolt 134 and nut 136 are not initially tightened sufficiently to
create a
sealing engagement between catalyst element 102 and wall 182 at room
temperature during installation, at the normal operating temperature during
operation, which is elevated due to the hot exhaust gas, a sealing engagement
is
conveniently obtained due to the increased force exerted on catalyst element
102.
[0063] Housing 100 may be used in a suitable catalytic converter, as
illustrated in FIGS. 15 to 26.
[0064] FIGS. 15 to 18 illustrate a stand-alone catalytic converter 200
which
includes housing 100. Catalytic converter 200 has an inlet 202 for receiving
an
exhaust gas and an outlet 204 for ejecting treated exhaust gas, and defines a
fluid
path for the gas to go through. Housing 100 is situated between inlet 202 and
outlet 204 so that the exhaust gas goes through openings 114 and 118, and
catalyst element 102 when it is installed.
[0065] Convert 200 may be built using materials selected so that the
converter may be repeatedly operated at temperatures up to 1200 2F.
13
CA 02595155 2007-07-27
[0066] In use, arms 130 may be pre-installed in housing 100. To install a
catalytic element, cover 108 is removed, exposing flow chamber 104 and access
channel 106. Catalyst element 102 is lowered into flow chamber 104 through
access channel 106, and rests on collar 126 so that its front face 180 abuts
rear
wall 182 of plate 110 (as shown in FIG. 8). Conveniently, the narrower top
portion
of collar 126 allows easy access. After catalyst element 102 is put in
position, pin
168 of bar 132 is inserted into aperture 142 of arm 130. As can be
appreciated,
when aperture 142 and pin 168 are properly sized, pressure bar 132 may swing
about while pin 168 is engaged with aperture 142, so as to allow enough room
for
the user to manipulate catalyst element 102 in flow chamber 104. In any case,
after catalyst element 102 is in position and pins 168 are inserted, pressure
bars
132 are positioned across and abut rear face 184 of catalyst element 102. Bar
132A is installed with its notch 164 facing away from catalyst element 102 and
bar
132B is installed with its notch 164 facing catalyst element 102. Bars 102 are
positioned so that sleeves 174 align with corresponding bore holes 122, 124. A
bolt 134 is then inserted into sleeve 174 of each bar 132 and the
corresponding
bore hole 122/124. Washer-gasket units 186, when used, are next put in place.
Nuts 136 are then coupled to threaded ends 179 of bolts 134 to tighten the
bolt
joint and clamp plate 110 and bars 132 so that plate 110 and bars 132 in turn
clamp catalytic element 102 with a desired pressure. As can be appreciated,
the
enlarged head 178 of bolt 134 and nut 136 may be flipped in some cases. The
orientation of bolts 134 may be selected depending on convenience and
available
space.
[0067] During installation, as discussed above, in some embodiments it
may not be necessary that the bolt joint is initially tightened to a great
extent. In
some embodiments, the position of aperture 142 may be selected such that, due
to restriction of the movement of end portion 144 of pressure bar 132 by arm
130,
the engagement or sealing between catalyst element 102 and plate 110 may be
less tight after initial installation than is required during operation.
Conveniently,
thermal expansion at elevated operating temperatures can automatically further
tighten the bolt joint thus providing the necessary pressure to form a sealing
engagement between catalyst element 102 and plate 110. Thus, all exhaust gas
14
CA 02595155 2007-07-27
will pass through catalyst element 102 and will not leak through a gap between
catalyst element and plate 110.
[0068] As pins 168 are positioned off-center on bars 132, when bars 132
are flipped, the distance from the nearer edge of bar 132 to wall 182 is
slightly
different. Depending on the particular catalyst element used, the orientation
of
pressure bars 132 may be reversed to accommodate the particular thickness of a
given catalyst element, which due to machine tolerance may vary to a certain
extent. For instance, pressure bars 132 may be designed to allow up to 1/16 in
variation in the thickness of catalyst element 102.
[0069] After catalyst element 102 is secured in position, cover 108 is
reinstalled in position to close off housing 102. As is conventional, a
seal/gasket
(not shown) may be provided between cover 108 and housing 100 to prevent
leakage of gas through gaps between cover 108 and housing 100.
[0070] During operation, exhaust gas enters converter 200 through inlet
202 and exits from outlet 204, as shown by the arrows in FIG. 18. As the hot
exhaust gas passes through flow chamber 104 of housing 100, it heats the
components in housing 100. During normal operation of a typical catalytic
converter, the operating temperature in housing 100 may reach, for example,
from
400 F to 1500 F, and typically about 900 F. The heated components therefore
expand. As discussed above, the axial thermal expansion of arms 130 and bolts
134 is less than the total axial thermal expansion of plate 110, catalyst
element
102 and pressure bars 132 at the operating temperature. As a result, catalyst
element 102 is more tightly pressed against plate 110, thus creating a tighter
seal
therebetween.
[0071] To achieve the desired tight seal during operation, the various
components may be formed of different materials with different thermal
expansion
coefficients. For example, bolts 134 and arms 130 may be made of carbon steel,
with an average thermal expansion coefficient of about 7.6 x 10-6 in/in. F;
the
frame of catalyst element 102, plate 110, and pressure bars 132 may be made of
stainless steel, with an average thermal expansion coefficient of about 9.6 x
10-6
CA 02595155 2007-07-27
in/in. F. The thermal expansion coefficients may be selected, such as within
the
range of 5 x 10'6 to 11 x 10'6 in/in. F, to adjust the pressure exerted on
catalyst
element 102 and plate 110 during operation.
[0072] Conveniently, the slidable engagement between aperture 142 of arm
130 and pin 168 of pressure bar 132 allows for thermal expansion of pressure
bar
132 along its longitudinal direction at high temperatures. To this end,
aperture
142 and pin 168 should be sized such that at the operating temperatures, pin
168
can still slide within aperture 142. This will prevent distortion of pressure
bar 132
due to thermal expansion at high temperatures.
[0073] As depicted in the drawings, no gasket or seal is placed between
catalyst element 102 and plate 110. Even without the gasket or seal, tight
seal
can be obtained due to the axial pressure exerted on catalyst element 102 by
pressure bars 132. However, in some embodiments, a gasket or seal (not shown)
may be placed between plate 110 and catalyst element 102. The gasket/seal may
need to be replaced after the pressure on the catalyst element is released or
when the catalyst element is removed/replaced.
[0074] When desired, catalyst element 102 may be removed from housing
100. To do so, cover 108 is first removed. Nuts 136 and bolts 134 are removed
to
un-tighten pressure bars 132. Pressure bars 132 may be removed or ends 146
may be swung towards rear plate 112 to provide some space to allow catalyst
element 102 to be disengaged from front plate 110 and taken out through access
channel 106.
[0075] FIGS. 19 to 21 illustrate a combination catalytic converter 300
which
includes both housing 100 and a silencer 302 for noise reduction. As depicted,
housing 100 is positioned upstream of silencer 302. In different embodiments,
silencer 302 may be positioned either upstream or downstream of housing 100.
[0076] In use, catalyst element 102 may be installed into converter 300
in a
similar manner as for converter 200, as illustrated in FIG. 19.
[0077] As depicted in FIGS. 19 to 21, housing 100 may be installed so
that
16
CA 02595155 2007-07-27
access channel 106 is on top. In a different embodiment, housing 100 may be
constructed and installed so that access channel 106 is inclined as
illustrated in
FIG. 22 so that it opens to the side. The orientation of access channel 106
may
be selected depending on the application and convenience.
[0078] Converter 300 conveniently provides both emission control and
noise reduction with an integrated unit, and can be used as a muffler.
[0079] FIGS. 23 and 24 illustrate another stand-alone catalytic converter
400 with housing 100, which includes a flow distributor or expander 402
positioned upstream of housing 100. Expander 402 is a cone shaped tube
positioned at or near the inlet 404 and may be substantially co-axial with the
inlet
opening. Expander 402 may be mounted on cross-beams 406 which are in turn
affixed to inlet 404. The size and shape of expander 402 and the distance
between expander 402 and catalyst element 102 may be selected to provide
uniform flow distribution over front face 180 of catalyst element 102.
[0080] FIGS. 25 and 26 illustrate another catalytic converter 500 with
housing 100 and a nested expander 502. As depicted, two cone-shaped tubes
504, 506 are nested. In other embodiments more than two expander tubes may
be nested to provide improved flow distribution. Expander 502 may be mounted
on cross-beams 508.
[0081] For instance, for a given application, Computational Fluid
Dynamics
(CFD) analysis may be performed using Finite Element Analysis (FEA) techniques
to determine the size and shape of expander 402, 502. Expander 402 or 502 may
be made of a material similar to that used for housing 100, such as stainless
steel,
carbon steel, or the like.
[0082] As now can be understood, housing 100 may be modified. For
example, the housing may have a rectangular opening instead of a circular
opening, as illustrated in FIGS. 27 and 28. As shown, housing 600 can
accommodate generally rectangular catalyst elements 602. In this case, more
than two pressure bars 604 may be used to secure each catalyst element 602.
17
CA 02595155 2007-07-27
Pressure bars 604 may be positioned across one another or parallel with each
other, as depicted. When desired, multiple catalyst elements 602 may be
positioned side by side, and both inlet and outlet openings of housing 600 may
be
provided with catalyst elements 602, as depicted. In alternative embodiments,
the
cross-sections of the catalyst element(s) and the housing may have the general
shapes of a different polygon or other suitable shapes.
[0083] Other modifications are also possible. As can also be appreciated,
bars 132 may be bolted to plate 110 in different manners in different
embodiments. For example, it may not be necessary to use nut 136. In one
embodiment, bore hole 122, 124 may be threaded and properly sized so that it
can threadedly engage threaded end 179 of bolt 134. In another embodiment, a
bolt body may be fixedly mounted on plate 110 with a threaded end extending
through sleeve 174 of pressure bar 132. A nut may be engaged with the threaded
end thus bolting pressure bar 132 to plate 110. The bolt body may be welded to
plate 110. Such an embodiment may be utilized when the bolt bodies would not
obstruct the mounting and dismounting of the catalyst element, such as when
rectangular catalyst elements are used.
[0084] Arms 130 may be replaced with another form of anchorage that can
releasably anchor an end of the pressure bar. In one embodiment, a bore or
slot
may be provided in the housing wall or a support arm for releaseably engaging
an
end of a pressure bar. In another embodiment, an end of the pressure bar may
be hingedly mounted to a housing wall. The end of the pressure bar may be
removably anchored or fixedly anchored, and may be pivotally connected to
housing using a different pivotal connection mechanism. In some embodiments,
it
may be more convenient if the pressure bar can be removed and replaced easily.
The anchorage may also have a different shape as arm 130. For example, the
anchoring arm may have a generally cylindrical or rectangular cross-section,
or
the like.
[0085] In one embodiment, both ends of the pressure bar may be bolted to
plate 110.
18
CA 02595155 2007-07-27
[0086] As depicted, collar 126 may form a ring for holding catalyst
element
102 and limiting its lateral movement relative to the axial direction of
opening 114.
The bottom portion of the ring may be wider to provide better support, while
the
top portion of the ring is narrower to provide easy access. In different
embodiments, the collar may have a different shape and it may not be necessary
that it forms a complete ring.
[0087] As can be appreciated, more than two catalyst elements may be
installed into flow chamber 104.
[0088] As can be appreciated, embodiments of the present invention have
certain advantages. For instance, in the embodiments shown in the figures,
installation and removal of catalyst element 102 is relatively simple and
convenient. The catalyst element can thus be conveniently inspected,
maintained
or replaced. The fixture assembly has a simple construction and can use
commonly available material and parts to construct. Modification of the
structure
is also relatively easy. For example, bolts of different lengths may be used
which
are readily available. It also does not require specialized tools to install
or remove
the pressure bars. The catalyst element is fairly stably secured using the
bolts
and the applied pressure or force can by easily adjusted. Even when the
catalyst
elements used have slightly varying sizes (particularly thickness), such as
due to
machine tolerance, good sealing between the catalyst elements and the front
plate can be achieved during operation.
[0089] The diameter of catalyst element 102 may also vary within a wide
tolerance range such as from -1/8 in to +1/4 in. Fixture assembly 128 is
flexible
enough to accommodate such, or even higher, variations.
[0090] As can also be understood by persons skilled in the art, some
commercially available catalyst elements have cores that can expand
significantly
during operation. For example, the central portion of the core can sometimes
telescope due to the pressure and heat applied to it by the exhaust gas.
Conveniently, restriction bar 120 and the projected central portion 150 of
pressure
bars 132 can limit expansion or telescoping of the catalyst core.
19
CA 02595155 2012-11-29
[0091] Other features, benefits and advantages of the embodiments
described herein not expressly mentioned above can be understood from this
description and the drawings by those skilled in the art.
[0092] Of course, the above described embodiments are intended to be
illustrative only and in no way limiting. The described embodiments are
susceptible to many modifications of form, arrangement of parts, details and
order of operation. The invention, rather, is intended to encompass all such
modification within its scope, as defined by the claims.
