WO2007131035A1

WO2007131035A1 - Exhaust gas treatment device

Info

Publication number: WO2007131035A1
Application number: PCT/US2007/068032
Authority: WO
Inventors: Christopher S. Weaver
Original assignee: Engine Fuel And Emissions Engineering, Inc.
Priority date: 2006-05-02
Filing date: 2007-05-02
Publication date: 2007-11-15

Abstract

A device 10 for treating an engine exhaust gas flow includes an inlet 12 and an expansion section (28A, 28B), which is fluidly connected to an engine. The expansion section is disposed between the inlet and a plurality of treatment modules (18, 20), such as catalytic converters or particulate filters, and is constructed to reduce the velocity and increase the pressure of the exhaust gas flow that enters the device such that the exhaust gas flow maintains a majority of the energy of the exhaust gas flow.

Description

Patent Application for EXHAUST GAS TREATMENT DEVICE

Inventor: CHRISTOPHER S. WEAVER

Assignee:

ENGINE, FUEL, AND EMISSIONS ENGINEERING, INC.

3215 Luyung Drive Rancho Cordova, CA 95742

BOYLE FREDRICKSON NEWHOLM STEIN & GRATZ, SC 250 East Wisconsin Ave., Suite 1030

Milwaukee, WI 53202 Telephone: 414-225-9755 Facsimile: 414-225-9753

Our Reference No. 318.005 U.S. Patent and Trademark Office Customer Account No. 23598 EXHAUST GAS TREATMENT DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S. C. § 119 from U.S. Provisional Patent Application Serial No. 60/746,203, filed on May 02, 2006 and entitled "Catalytic Converter Assembly," which is herein expressly incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to exhaust treatment systems and, more particularly, to a modular device containing several distinct units for filtering and/or converting exhaust byproducts from internal combustion engines.

2. Discussion of the Related Art

During operation of an internal combustion engine, a fuel is burned in a combustion chamber of the engine. The combustion of the fuel heats the gas in the cylinder and displaces a piston of the engine and thereby generates the engine operative force. Byproducts of this combustion include pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM), and oxides of nitrogen (NOx), all of which contribute to air pollution. Increasining, government regulations require that the exhaust gases be treated to reduce pollutant emissions. In the case of diesel engines, the exhaust gases are often treated by diesel particulate filters (DPFs) and/or catalytic converter treatment devices. A DPF traps or filters particulate matter such as smoke carried on the exhaust gas flow, and prevents this matter from being discharged into the atmosphere. A catalytic converter generally includes a catalyst that promotes chemical reactions whereby harmful byproducts of combustion, such as CO and NOx are reacted to produce less objectionable byproducts such as carbon dioxide, nitrogen gas, and water vapor. The capacity of any particular exhaust treatment device of a particular size, be it a catalytic converter, a particulate trap, or some other device, is finite. If the exhaust gas flow through the device exceeds this capacity, the result will be a reduction in pollution control efficiency, unacceptable increase in the pressure drop through the device ("backpressure"), or both. Catalytic converters and diesel particulate filters are generally mass-produced as round, oval, or elliptical elements of a size suitable for on-road truck applications - i.e about 100 to 400 horsepower. More powerful engines used in locomotives, marine vessels, and earthmoving equipment typically have larger exhaust flows for which the typical catalytic converter or particulate filter would have insufficient capacity. Engines of such magnitude are relatively few in number, rendering the production of large single element treatment devices of sufficient capacity to effectively treat the exhaust streams from such engines cost prohibitive. Assemblies of multiple catalysts or other treatment devices manifolded together have sometimes been used to satisfy the exhaust treatment requirements such engines. Such simplistic combination is generally inadequate for mobile engine systems such as locomotive or marine applications. That is, such systems are suspect to frequent maintenance and commonly fail due to the rigors associated with the operational environment. Still other exhaust treatment systems, such as for use in power plant applications, use an array of large square catalytic monoliths. These monolithic combinations are not without their drawbacks. The large size, high cost, and low- vibration tolerance render them unsuitable for many various applications, including mobile equipment.

The need has therefore arisen to provide a cost-effective, versatile technique for forming a catalytic converter, particulate filter, or other exhaust treatment device from a plurality of modules of relatively inexpensive and durable "stock."

Effective exhaust treatment devices also should be constructed to achieve acceptable dwell time in the device without generating excessive backpressure. It is desirable to generate some backpressure across the treatment device to force the exhaust gases through the active components of the device. Backpressure is generated when the kinetic energy of the flowing gases is converted to pressure by decelerating the flowing gases. However, during turbulent flow, some of this kinetic energy is lost through friction rather than being converted into pressure. Conventional wisdom, therefore, is to minimize or eliminate directional changes of gas flow through a treatment device in order to eliminate turbulence. Conventional design wisdom therefore dictates that devices that impart sharp directional changes to gas flow are to be avoided and that exhaust treatment devices should instead be designed such that the gases flow straight through the treatment device. However, even in these devices, the gases experience relatively small velocity drops and, accordingly, relatively small pressure increases. Versatility and/or compactness in design that could otherwise be achieved through the use of plenums and similar devices also are lost. Accordingly, it would be desirable to provide a robust exhaust treatment device that provides for efficient passage and flow of exhaust gas therethrough without detrimentally affecting engine performance and versatility of exhaust treatment package shape.

SUMMARY OF THE INVENTION

The present invention is directed to a method and exhaust gas treatment device that overcomes the aforementioned problems. The treatment device includes an inlet that is fluidly connected to an engine. An expansion section is disposed between the inlet and a plurality of treatment modules and is constructed to reduce the velocity and increase the pressure of the exhaust gas flow that enters the treatment device such that the exhaust gas flow maintains a majority of the energy of the exhaust gas flow. The treatment modules may, for instance, comprise catalytic monoliths or particulate filters.

According to one aspect of the invention, an exhaust treatment device is disclosed which includes a first plate and a second plate generally aligned with the first plate and offset therefrom. The first plate and the second plate each include a plurality of openings therethrough. A treatment module is mounted in or over each of the openings and an expansion section is formed between the first plate and the second plate. The expansion section is fluidly connected to an inlet of the exhaust treatment device and is constructed to decelerate and pressurize an exhaust gas flow directed into the exhaust treatment device. In accordance with another aspect of the present invention, an exhaust treatment device includes an inlet constructed to be fluidly connected to an exhaust of an internal engine. The exhaust treatment device has an outlet that is fluidly connected to the inlet and directed to atmosphere. A first gas path is directed in a first direction and formed between the inlet and the outlet. A second gas path is formed between the inlet and the outlet and isolated from the first gas path and has a direction that is generally opposite the first direction over at least a portion of the second gas path.

According to a further aspect of the invention, an exhaust treatment device has a body, a plurality of exhaust treatment modules, and first and second cover(s). The body has an inlet and a first set of openings and a second set of openings generally opposite the first set of openings. The treatment modules are mounted in the openings. The first cover is disposed over the first set of openings and constructed to sealingly engage the body and is fluidly connected to an outlet of the exhaust treatment device. The second cover is disposed over the second set of openings and is constructed to sealingly engage the body and is fluidly connected to the outlet.

According to yet other aspects of the invention, an exhaust treatment device has an inlet and an expansion section, which are fluidly connected to an engine. The plenum has a length, and an upper wall and a lower wall. Each of the upper and lower walls has an opening extending therethrough. Treatment modules are mounted to the plenum upper and lower walls, fluidly communicating with the openings through them. The treatment modules on the upper and lower walls extend generally away from each other and are arranged generally perpendicular with respect to the length of the plenum. In some implantations, the invention comprehends a method of treating exhaust gas. The methods includes, e.g., first, directing a volume of exhaust gas through an inlet, of an exhaust gas treatment device, at a first exhaust gas flow velocity and a first exhaust gas pressure. Next the volume of exhaust gas can be directed into an expansion section, where magnitude of the exhaust gas flow velocity is decreased, whilst the magnitude of the exhaust gas pressure is increased. Further, the volume of exhaust gas can be directed into a plenum and distributed through a plurality of treatment modules.

Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and the accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred exemplary embodiment of the invention is illustrated in the accompanying drawings in which like reference characters represent like parts throughout.

FIG. 1 is a perspective view of an exhaust treatment device according to a first embodiment of the present invention with a portion of a cover thereof removed. FIG. 2 is a cross-section of the treatment device shown in FIG. 1 along line 2-2. FIG. 3 is a perspective view of an exhaust treatment device according to a second embodiment of the present invention with a portion of a cover thereof removed.

FIG. 4 is a cross-section of the treatment device shown in FIG. 3 along line 4-4. FIG. 5 is a perspective view of an exhaust treatment device according to a third embodiment the present invention with a cover removed therefrom.

FIG. 6 is a cross-sectional view of the treatment device shown in FIG. 5 along line 6-6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred exemplary embodiments of the exhaust gas treatment device of the present invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout.

FIG. 1 shows a treatment device 10 according to a first embodiment of the present invention. Treatment device 10 is configured for use with a large diesel engine used, for example, to propel a marine vessel. Treatment device 10 includes a main portion, such as body 11, and at least one, preferably multiple, treatment assemblies 18, 20, operably connected to the body 11. In the assembled device 10, the exhaust gases flow (i) into body 11, (ii) out of body 11 and into the treatment assemblies 18, 20, then (iii) out of the treatment assemblies 18, 20 and back into body 11, and finally (iv) out of the body 11, exiting the device 10 in a treated condition. Referring now to FIGS. 1, 3, and 5, body 11 includes an inlet 12, and outlet 14, and a plenum 26 spanning between and connecting the inlet 12 and outlet 14 to each other. Inlet 12 includes a flange 16 which is connected to an inlet tube 112 that is, in turn, connected to an expansion section 28 A. The flange 16 of inlet 12 is constructed to simplify the attachment of treatment device 10 to an exhaust system of the associated internal combustion engine. Accordingly, the flange 16 is shaped and sized based on the intended end use application, be it a generally annular flange as seen in FIGS. 1-4, or a generally rectangular flange as seen in FIGS. 5-6. Regardless, the flange 16 of inlet 12 is, for example, bolted, clamped, and/or welded to, an exhaust pipe that extends from the engine exhaust manifold.

As shown in FIGS. 1-4, inlet tube 112 is a hollow cylindrical member which connects the flange 16 to an end of the expansion section 28 A. The circumferential sidewall of inlet tube 112 joins the sidewall of inlet expansion section 28 A, thus defining a generally circular opening or passage between the inlet tube 112 and the expansion section. However, inlet tube 112 is optional, whereby in some embodiments, such as those seen in FIGS. 2 and 4, flange 16 is connected directly to the end of expansion section 28 A.

Still referring to FIGS. 1-4, expansion section 28 A has a length, a width which varies along the length, and defines, for example, an expanding volume conduit. The expansion section 28A has a minimum width near the flange 16 and a maximum width near plenum 26. Since expansion section 28A has a varying width dimension and a relatively constant height or thickness dimension, it defines different cross-sectional areas at different locations along the length of the inlet 12. As seen in FIGS. 1 and 3, the top and bottom walls 50 and 52 of expansion section 28A are generally triangular or wedge-shaped, when viewed from a top, plan view perspective. The top and bottom walls 50 and 52 are vertically spaced from and extend generally parallel to each other. Optionally, the top and bottom walls slightly vertically diverge from each other as they approach plenum 26. Sidewalls 54 and 56 stand generally upright and extend between respective lateral edges of the top and bottom walls 54 and 56, connecting them to each other. Accordingly, the sidewalls 54 and 56 slant toward each other, in the direction of the inlet tube 112 and likewise slant outwardly away from each other in the direction of plenum 26. Thus, the ends of sidewalls 54 and 56 proximate flange 16 are relatively nearer each other, while the other ends of sidewalls 54 and 56, proximate plenum 26, are relatively further displaced from each other.

Referring now to FIGS, 1, 3, and 5, each end of expansion section 28A corresponds in shape and configuration to, for example, the shape and configuration of the structure(s) that it interfaces with. For example, a first end 128 of expansion section 28A corresponds in shape and configuration to the inner or outer perimeter shape of flange 16 or inlet tube 112. Accordingly, in embodiments which incorporate inlet tubes 112 which are circular in cross-section, the first end 128 of the expansion section 28A is correspondingly generally round or circular (FIGS. 1 and 3). From this first end of expansion section 28A, the circumferential sidewall transitions into the generally planar wall segments, exemplarily described and shown as top and bottom walls 50 and 52, as well as sidewalls 54 and 56. A second end 130 of expansion section 28A corresponds in shape and configuration to an end of plenum 26 (FIGS. 1 and 3). Thus, as seen in FIG. 1, 3, and 5, the second end 130 of the expansion section 28A has a generally rectangular perimeter shape. The second end 130 can define various other perimeter shapes, depending on the particular configuration of, for example, the size, shape, and configuration of the plenum 26, such that they operably interact.

In some configurations of the device 10, such as those of FIGS. 5 and 6, the inlet 12 has no expansion section. In these embodiments, the inlet 12 is substantially uniform in cross- section area, along its length. Thus, as illustrated in FIGS. 5 and 6, the inlet 12 can have generally rectangular top and bottom walls 52, 54, and a parallel pair of sidewalls, which in combination define, e.g., a rectangular, hollow, column; optionally other configurations are implemented, as desired. In these configurations, the expansion section 28 A is part of the plenum 26, explained in greater detail elsewhere herein, in lieu of being part of the inlet 12.

With reference to FIGS. 1-4, outlet 14 is in many ways similar to, preferably generally a mirror image of, and even more preferably is at least substantially identical in its dimensions to, inlet 12. Accordingly, outlet 14 tapers down from a relatively larger, rectangular, end 230 that are connected to plenum 26, to a relatively smaller round or circular end 228. Like inlet 12, outlet 14 includes a flange 16 which is connected to a cylindrical and hollow outlet tube 114 that, in turn, is connected to a tapering section 28B which is largely an analogue of expansion section 28 A. The flange 16 of outlet 14 is constructed to simplify the attachment of treatment device 10 to the remainder, such as the downstream portion, of the engine exhaust system. Accordingly, the flange 16 of outlet 14 is, for example, bolted, clamped, and/or welded to a tail pipe, an exhaust tip, or other exhaust piping, required by the particular size and clearance constraints of the vehicle or end-use environment.

Outlet tube 114 extends from the inward facing surface of flange 16, toward the remainder of the device 10. The circumferential sidewall of outlet tube 114 joins the end 228 of the sidewall of tapering section 28B. This intersection defines a generally circular opening or passage between the outlet tube 114 and the tapering section 28B. Similar to inlet 12, outlet tube 114 is optional, whereby flange 16 can be connected directly to the end 228 of tapering section 28B.

As seen in FIGS. 1 and 3, the perimeter shapes of the top and bottom walls 60, and 62 of tapering section 28B are generally triangular or wedge-shaped. The top and bottom walls 60 and 62 are vertically spaced from and extend generally parallel to each other. The outer lateral edges of the top and bottom walls 60, 62 are connected by sidewalls 64 and 66 The sidewalls 64 and 66 slant toward each other, in the direction of the outlet tube 114, and thus slant outwardly away from each other, in the direction of plenum 26. Thus, the ends of sidewalls 64 and 66 proximate flange 16 are relatively nearer each other, while the other ends of sidewalls 64 and 66, proximate plenum 26, are relatively further displaced from each other. Correspondingly, the tapering section 28B has a minimum width near the flange 16 and a maximum width near plenum 26, and defines different cross-sectional areas at different locations along the length of the outlet 14.

Now referring to FIGS. 5 & 6, some implementations of outlet 14 do not include a tapering section. Such implementations can be, instead, generally uniform in cross-section along their lengths. Thus, in such embodiments, the outlets 14 can each have rectangular top and bottom walls 60, 62 and parallel rectangular sidewalls 64, 66, which in combination define, e.g., a rectangular, hollow, column, or other configurations having uniform cross-sections.

Referring to FIGS. 2, 4, and 6, plenum 26 is, e.g., a partially enclosed structure which extends between and connects the inlet 12 and outlet 14. The plenum 26 has one open end 68, which is fluidly coupled to inlet 12, and one closed end wall defined by partition plate 32.

Plenum 26 further includes an upper wall 70, a lower wall 72, first and second sidewalls 74 and 76, and optionally a collecting chamber 90. The sidewalls 74, 76 are generally upright and extend between and connect the outer edges of upper and lower walls 70, 72. The inwardly facing surfaces of, e.g., partition plate 32, sidewalls 74, 76, and upper and lower walls 70, 72, define a void or cavity, such as distribution cavity 80 therebetween.

Referring to FIGS. 5 and 6, expansion section 28 A can be implemented as part of the plenum 26, whereby the expansion section of inlets 12 is no longer required for suitable functionality of the device 10. In these configurations, the expansion section 28A can be integral or otherwise directly incorporated as part of the plenum 26. Correspondingly, in devices 10 such as those in FIGS. 5 and 6, the expansion section 28 A end opening and the beginning of distribution cavity 80 are generally non-discernable.

Referring now to FIGS. 1-6, each of the upper and lower plenum walls 70, 72 has at least one opening 34 extending therethrough. The openings 34 permit access and fluid flow through the upper and lower walls 70, 72, and thus between various portions of the exhaust gas treatment device 10. In other words, an incoming stream 30 of gas flows into the distribution cavity 80, where it is separated into substreams 40 and 42 that flow through the openings 34 of upper and lower walls 70 and72, respectively. This distribution and flow pattern is explained in greater detail elsewhere herein.

Referring now to FIGS. 1 and 2, the optional collecting chamber 90 can be located at the end of plenum 26 adjacent outlet 14. The collecting chamber 90 is a void space or cavity defined between end portions of the upper and lower plenum walls 70, 72, which are adjacent outlet 14, and the outwardly facing surface of partition plate 32. Apertures 82 extend through the ends of the upper and lower walls 70 and 72, respectively, opening into the collecting chamber 90. Collecting chamber 90 opens into and fluidly communicates with the outlet 14. Accordingly, the collecting chamber 90 intakes gases, i.e., substreams 40 and 42, through the apertures 82. The two flows of gases or substreams 40, 42 collect in the chamber 90, combine into a single gas flow, then exit the chamber 90 and flow into the outlet 14. Notwithstanding, and now to FIGS. 3-6, in some implantations of the device 10, the plenum 26 is devoid of a collecting chamber 90, whereby the device 10 includes two outlets 14 to exhaust two distinct outputted flows of gases, explained in greater detail elsewhere herein. Referring to FIGS. 1 through 4, it is apparent that the system could also be configured so that the exhaust gases to be treated flow in the reversed direction, i.e. entering through the outlet(s) 14, passing through the space enclosed by covers 36, 38, and then passing through the treatment assemblies 18, 20 into plenum 26. For example, treatment using two different types of treatment assemblies could be accomplished by connecting two of the assembly of FIG 3 and 4 "back to back" so that the gases flowed from the single inlet 12 to the dual outlets 14 in the first, and from dual inlets 14 to a single outlet 12 in the second.

Referring to FIGS. 2, 4, and 6, within the plenum 26, the outwardly facing surfaces, or other portions, of the upper and lower walls 70, 72, preferably include mounting stracture(s) suitable for operably coupling, e.g., various components of the treatment assemblies 18, 20 thereto. As one example, the upper and lower walls 70, 72 can include various attaching mechanisms or fasteners for connecting the covers 36, 38 to the plenum 26. As desired, the upper and lower walls 70, 72 can extend outwardly beyond the perimeter defined at least partially by the plenum sidewalls 74, 76. Such outwardly extending portions of the upper and lower walls 70, 72 define and serve as perimeter flanges 116 or mounting lips which can accept hardware therethrough while mounting the treatment assemblies 18, 20 to the plenum 26. As another example of suitable mounting structure(s) for operably coupling, e.g., various components of the treatment assemblies 18, 20 to the plenum 26, the upper and lower plenum walls 70, 72 include structures or devices to facilitate mounting the modules 24 to the plenum 26. As one example, the upper and lower walls 70, 72 can include generally annular receiving structures, mounting structures, holding devices, or other suitable hardware, concentrically mounted around the openings 34. Such annular mounting structures are adapted and configured to suitably hold, optionally releasably hold, the modules 24 in a sealed manner against the respective portions of the plenum 26. As another example, a plurality of fasteners 22, or other suitable hardware such as various threaded rods, studs, bolts, or screws secure the modules to, for example, various outer surfaces of plenum 26. The fasteners 22 can extend through or outwardly from the upper and lower walls 70, 72, and collectively concentrically surround the perimeter of openings 34, enabling the attachment of modules 24 to plenum 26.

Still referring to FIGS. 2, 4, and 6, and specifically regarding the treatment assemblies 18, 20, they are preferably removably attached to, optionally non-removably fixed to, the plenum 26. Each of the treatment assemblies 18, 20 includes at least one treatment module 24 and cover 36, 38. The treatment modules 24 perform the desired treatment function(s), and thus to some extent define the overall functionality and use of the device 10. If, for instance, they are particulate filters, they remove soot and other particulates from the exhaust stream. If they are catalytic converters, they oxidize or otherwise convert exhaust by-products such as CO to less objectionable byproducts such as CO₂. The treatment modules 24 are preferably "stock" modules 24 of the type that are widely available for on-road diesel truck applications, as well as various ones for off-highway diesel truck applications, as desired and based on the intended end use environment of the exhaust treatment device 10.

The illustrated treatment modules 24 are round in cross-section, but could be oval, elliptical, or any other shape. The number and nature of the treatment modules 24 will be application specific. Thus, the modules 24 can define, e.g., sets of modules, whereby all the modules 24 attached to the upper plenum wall 70 are a single set and all the modules 24 attached to the lower plenum wall 72 are another single set. The overall shape of the device 10, including the relative relationships of the treatment modules 24 (i.e., the number of rows of modules 24 and the number of modules 24 in each row or set), can also be tailored to accommodate space constraints and other geometrical characteristics of the specific application.

10 Referring to FIGS. 1-4, in some implementations, the treatment modules 24 are substantially cylindrical and include an upper end 124 and a lower end 126 which can include a radially extending flange 127 about its entire circumference. Such flange 127 provides mounting structure to operably couple the treatment modules 24 to the plenum 26, alone, by way of fasteners 22, or otherwise. Also, the flange 127 is adapted and configured to provide a suitable seal between the module 24 and the plenum 26, whereby the lower end 126 is sealingly attached to the plenum 26. In such configuration, since the gas which flows into the distribution cavity 80 must exit through the openings 34, such gas must correspondingly flow through the treatment modules 24. This ensures that all gas that enters the device 10 will be suitably treated by the modules 24. The treated gas, which emanates and is emitted from the modules 24, is retained in the device and separated from the ambient by the covers 36, 38.

Referring again to FIGS. 1-6, each of the covers 36 and 38 serves as, for example, a cap or lid which covers the treatment modules 24, as well as corresponding portion of plenum 26. The covers can include a generally planar top wall 150, which can be generally rectangular, as in the embodiments seen in FIGS. 1-4. Optionally, the perimeter of the cover top walls 150 define other polygonal shapes such as those shown in FIGS. 3 and 4, or yet other shapes depending on the particular end configuration.

Opposing sidewalls 152 and 154 extend perpendicularly from respective opposing edges of the top wall 150. Likewise, opposing end walls 156 and 158 extend perpendicularly from respective opposing end edges of the top wall 150. The combination of the cover top walls 150, sidewalls 152, 154, and end walls 156, 158 defines a box-like structure with an open bottom portion that extends into an interior cover cavity 236, 238. It is the cover cavities 236, 238, in particular, which house the treatment modules 24 and provide the void space for the treated gases to emit from the modules 24 and flow through the treatment assemblies 18, 20. Regardless of the particular design, in the end configuration to device 10, the covers 36, 38 and the plenum 26 provide a sealed interface therebetween whereby the distribution cavity and the cover cavities 236, 238 fluidly communicate with each other, yet are substantially sealed and separated from the ambient.

In some implementations, a cover flange 216 extends generally perpendicularly out from the lower edges of the cover sidewalls 152, 154 and endwalls 156, 158, about the entire perimeter of the cover bottom opening. The cover flanges 216 are sized, adapted, and configured

11 to operably couple with the corresponding flange 116 of plenum 26. The interfacing flanges 116, 216 are attached to each other by way of, e.g., fasteners 22. Fasteners 22 could be any of rivets, screws, or other removable and replaceable connectors. Optionally, the cover flange 216 can be mounted directly to the upper and lower plenum walls 70, 72, for example, if the device does not incorporate a plenum flange 116. Also, if servicing of treatment device 10 is not desired, the covers 36, 38 and thus the treatment assemblies 18, 20, can be welded or riveted to the plenum 26, whereby the treatment assemblies 18, 20 are non-removably fixed the body 11.

The overall design and configuration of the exhaust gas treatment device 10 imparts and provides various desired fluid-dynamic occurrences within the various components. Therefore, the gas flow paths, patterns, and characteristics within the treatment device 10 are the result of various structural attributes of the various components and their particular relationships relative to each other. In particular, the treatment device 10 can minimize kinetic energy losses through turbulence. This is, to at least some extent, achieved by way of the expansion section 28 A, whether it is part of inlet 12 as seen in FIGS. 1-4, or integral with plenum 26 as seen in FIGS. 5- 6.

In other words, the treatment device 10 preferably is configured to impart flow characteristics to the incoming gas flow or stream 30 that minimize kinetic energy losses through turbulence. This does not necessarily mean that turbulence must be minimized. Instead, the device 10 is preferably designed to minimize high velocity turbulence so that pressure can increase as a result of a decrease in flow velocity, as is mandated by Bernoulli's Equation, which, for steady, frictionless incompressible flow through a conduit, can be expressed as:

P/γ+ V² / 2g = Constant where: EQUATION 1 P = pressure,

V = velocity

7= the specific weight of the fluid, and g = the acceleration of gravity.

Therefore, as V decreases, P must increase and vice versa.

For a steady flow:

12 V = Q / A, EQUATION 2

Where:

Q = volumetric flow rate, and A = the cross-sectional area of the conduit.

Therefore, as long as friction is negligible, increasing the cross-sectional area of the conduit reduces the velocity, and pressure increases to compensate. This is the case where there is a gradual increase in cross-section that results in non-turbulent expansion flow.

As stated above, these equations assume frictionless flow. However, a sudden change in cross-section (or in direction of flow) results in the generation of turbulence and resultant internal friction in the fluid. As a result, the pressure will increase less than predicted by Bernoulli's Equation.

The amount of energy lost due to friction is proportional to the change in kinetic energy of the fluid which, in turn, is proportional to ΔV². From this, it is apparent that frictional losses due to turbulence are substantially more troublesome at high velocities than at low velocities. As such, one can accept a certain amount of turbulence and resultant frictional losses in a system if the gas flow is caused to undergo deceleration, with a resultant pressure increase, prior to being subjected to turbulent flow. Hence, contrary to conventional wisdom, a treatment device can impart sharp changes to directional flow and/or sudden expansion of flow if the device is configured to decelerate and pressurize the gas prior to imparting the directional changes to or rapid expansion of the flowing gas.

This effect can be achieved by designing the treatment device 10 such that the cross- sectional area of the flow increases gradually going from the entrance prior to undergoing sharp expansion or direction changes in order to minimize the frictional losses due to high velocity turbulence, such as, by way of expansion section 28 A. The subsequent sudden 90 degree change in direction of flow, as the gas flow is directed to the treatment modules 24, results in a loss of energy proportional to the square of the velocity; but the amount of energy lost is small because the exhaust velocity is already relatively low.

For example, in expanding from a 6" diameter pipe to a 6" x 15" rectangular conduit, which can be the dimensions of expansion section 28 A (FIGS. 1-4), the area of a conduit increases from 28 in² to 90 in², and the velocity must fall by the same proportion — 28/90 =

13 .314. The loss of kinetic energy is thus proportional to 0.314², or only 0.1 times the kinetic energy loss that would occur if the expansion section had not been inserted upstream of the treatment modules. To achieve this effect, as shown in FIGS. 2, 4, and 6, the expansion sections 28 A are, at least to a large extent, upstream of plenum 26 and treatment modules 24. During use, a gas flow or stream 30 is directed into expansion section 28A before entering the plenum 26. The construction and relative dimensions of expansion section 28A and plenum 26 is such that the velocity of the gas stream 30 decreases in the expansion section 28A, while the pressure within plenum 26 and expansion section 28A increases, before significant turbulence is induced as the volume of gas flows into the plenum 26. Correspondingly, a majority of the energy of the flowing gas stream 30 is maintained.

The gas continues to flow through the plenum 26, where its generally axial flow pattern is restricted by the partition plate 32. The volume of gas which enters the plenum 26 as stream 30 is thereby divided into smaller volumes which flow along generally parallel paths as substreams 40 and 42, which through the plenum openings 34 in upper and lower plenum walls 70, 72, respectively. Stated in other terms, the individual gaseous flowing components of within each of the substreams 40 and 42 flow parallel to each other. The substreams 40, 42 themselves, flow generally parallel to each other, but in opposite directions. Next, the substreams 40, 42 of gas flow through and are treated by the treatment modules 24.

The flow directions and paths of substreams 40, 42 correspond to the location, size, and other characteristics of the plenum openings 34. As seen in FIGS. 2, 4, and 6, the substreams 40, 42 that enter treatment assembly 18 flow in a direction substantially opposite the direction of the substreams 40 that enter treatment assembly 20. Thus, some of the volume of gas which enters the plenum 26 flows through cover cavity 236 and thus through treatment assembly 18, while the remainder flows through cover cavity 238 and thus through treatment assembly 20. In devices 10 which include a collecting chamber 90, the substreams 40, 42 merge in collecting chamber 90, then flow into and through outlet 14 as a unitary stream of flowing gas. For embodiments devoid of a collecting chamber, such as those seen in FIGS. 3-6, the substream 40 which flows through the treatment assembly 18 ultimately flows through and out of the outlet 14 attached to cover 36. Corresponding, the substreams 42 that flow through treatment assembly 20 ultimately flow through and out of the outlet 14 attached to cover 38. Even in such multiple

14 outlet configurations, if desired, the exhaust gases can be recombined further downstream by, for example, a Y-pipe or other suitable device.

Hence, regardless of the particular end use design and configuration, exhaust treatment devices 10 include expansion sections 28 A. Whether this expansion sections 28 A are part of inlets 12, or plenums 26, expansion sections 28 A allow for uninterrupted penetration of an inlet gas stream 30 along a majority of the length of the treatment device, as defined by an inlet axis of gas. Such construction ensures that a majority of the exhaust gas energy is maintained in the flow of the exhaust gas and not transmitted into the treatment device in the form of heat or gas system inefficiency. Many changes and modifications may be made to the present invention without departing from the spirit thereof. The scope of some of these changes is discussed above. The scope of others will become apparent from the appended claims.

15

Claims

CLAIMSI claim:

1. An exhaust treatment device comprising: an inlet; a plenum having at least a first plenum wall and a second plenum wall, each of the first and second plenum walls being substantially flat and having at least one opening extending therethrough; a treatment module mounted in or over each of the openings in the plenum walls; and an expansion section fluidly connecting the inlet and the plenum, wherein the expansion section reduces the velocity and increases the pressure of an exhaust gas flow directed into and flowing through the exhaust treatment device.

2. The exhaust treatment device of claim 1, further comprising a first cover constructed to sealingly engage the first plenum wall and defining a first cavity therebetween.

3. The exhaust treatment device of claim 2, further comprising a second cover constructed to sealingly engage and enclose the second plenum wall and defining a second cavity therebetween.

4. The exhaust treatment device of claim 3, wherein the first cavity and the second cavity are fluidly separated from the expansion section by the treatment modules.

5. The exhaust treatment device of claim 1, wherein the first plenum wall and the second plenum wall are generally transverse to an axis between an inlet and an outlet of the exhaust treatment device.

6. The exhaust treatment device of claim 1, wherein the treatment modules are replaceable.

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7. The exhaust treatment device of claim 1, wherein a cross-sectional area of an outlet of the expansion section is substantially greater than a cross-sectional area of an inlet to the exhaust treatment device.

8. An exhaust gas treatment device, comprising: an inlet constructed to be fluidly connected to an exhaust of an internal engine; an outlet fluidly connected to the inlet and directed to atmosphere; a first gas path directed in a first direction and formed between the inlet and the outlet; a second gas path formed between the inlet and the outlet and isolated from the first gas path and having a direction that is generally opposite the first direction over at least a portion of the second gas path; and a plurality of treatment modules disposed between the inlet and the outlet, wherein a first set of the plurality of modules forms a portion of the first gas path and a second set of the plurality of modules forms a portion of the second gas path.

9. The treatment device of claim 8, further comprising a partition plate constructed to support the first set of treatment modules and another partition plate constructed to support the second set of treatment modules.

10. The treatment device of claim 9, wherein the partition plate and the first set of treatment modules and the other partition plate and the second set of treatment modules fluidly separate an inlet chamber and a first outlet chamber and a second outlet chamber.

11. The treatment device of claim 10, further comprising a first cover constructed to sealing engage the partition plate and enclose the first set of treatment modules within the first outlet chamber and a second cover constructed to sealing engage the another partition plate the enclose the second set of treatment modules within the second outlet chamber.

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12. The treatment device of claim 8, wherein the first gas path includes a plurality of fluidly isolated and commonly directed gas paths.

13. The treatment device of claim 12 wherein the second gas path includes a plurality of fluidly isolated and commonly directed gas paths which are directed in a generally opposite direction of the plurality of fluidly isolated and commonly directed gas paths of the first gas path.

14. An exhaust treatment device comprising: a housing having an inlet and an outlet; a plurality of treatment modules disposed in said housing; an expansion section between said inlet to said treatment modules, said expansion section being configured to cause gases flowing therethrough to expand, change direction, and decelerate; and an exhaust passage leading from said treatment modules to said outlet.

15. The treatment device of claim 14, wherein each of said treatment modules comprises at least one of catalytic converter modules and particulate filters.

16. The treatment device of claim 14, wherein said supply passage includes a bend of at least 90°.

17. A method comprising: feeding an exhaust gas flow from an internal combustion engine to an inlet of a housing of an exhaust gas treatment device; causing said gas flow to expand gradually, decelerate, and pressurize, and then sharply change direction and/or expand, then directing said gas flow through a plurality of treatment modules in parallel streams; and exhausting said gas flow from said housing.

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18. The method of claim 17, wherein the gas flow sharp change of direction defines a generally perpendicular change in direction.

19. The method of claim 17, wherein a volume of gas that enters the gas treatment device divides into first and second distinct gas flow segments, the first and second gas flow segments traveling in generally opposing directions.

20. The method of claim 19, wherein the volume of gas divides into a first pair of gas flow segments and a second pair of gas flow segments, the first and second pairs of gas flow segments traveling in generally opposing directions.

21. An exhaust treatment device comprising: an inlet; an outlet in fluid communication with the inlet; a plenum having a length, an upper wall and a lower wall, each of the upper and lower walls having an opening extending therethrough; a first treatment module mounted to the plenum upper wall, fluidly communicating with the opening of the upper wall; and a second treatment module mounted to the plenum lower wall, fluidly communicating with the opening of the lower wall, wherein the first and second treatment modules extend generally away from each other and are arranged generally perpendicular to the length of the plenum.

22. The treatment device of claim 21 , wherein one of the upper and lower walls has multiple openings extending therethrough, and each of the multiple openings has a treatment module fluidly communicating therewith.

23. The treatment device of claim 21 , wherein each of the upper and lower walls has multiple openings and each of the multiple openings has a treatment module fluidly communicating therewith.

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24. The treatment device of claim 21 , further comprising a first cover attached to the plenum and overlying the plenum upper wall and a second cover attached to the plenum and overlying the plenum lower wall.

25. The treatment device of claim 21, wherein the inlet defines a length dimension and a width dimension that varies in magnitude along such length.

26. The treatment device of claim 25, further comprising a flange attached to an end of the inlet, distal the plenum, and wherein the inlet defines a first cross-sectional area proximate the flange and a second cross-sectional area proximate the plenum, the magnitude of the second cross-sectional area being greater than the magnitude of the first cross-sectional area.

27. A method of treating exhaust gas comprising: directing a volume of exhaust gas through an inlet, of an exhaust gas treatment device, at a first exhaust gas flow velocity and a first exhaust gas pressure; directing the volume of gas into an expansion section and reducing the magnitude of the exhaust gas flow velocity and increasing the magnitude of the exhaust gas pressure; directing the volume of exhaust gas into a plenum; and distributing the volume of exhaust gas out of the plenum through a plurality of treatment modules.

28. The method of claim 27, further comprising the step of distributing the volume of gas in generally opposite directions.

29. The method of claim 27, further comprising the step of directing the volume of gas out of the device as a single flow stream.

30. The method of claim 27, further comprising the step of directing the volume of gas out of the device as a plurality of flow streams.

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