OXIDATION OF ENGINE GENERATED PARTICULATE MATTER UTILIZING EXHAUST MANIFOLD GASES

Abstract

An improved system and method for treating exhaust emissions from a combustion engine is provided. The system provides improved arrangements for oxidizing particulate matter away from a particulate filter by utilizing elevated temperature exhaust manifold gases.

Claims

1. A system for oxidizing particulate matter of an engine, the system comprising: a particulate matter oxidation system for oxidizing particulate matter output from the engine; an exhaust manifold in fluid communication with the particulate matter oxidation system, wherein exhaust gases from the exhaust manifold are used to oxidize particulate matter produced by the engine; a settling tank in fluid communication with the exhaust manifold and the particulate matter oxidation system; a particulate filter downstream from the particulate matter oxidation system for filtering particulate matter from at least one of the engine and the particulate matter oxidation system.

2. The system of claim 1, wherein the particulate matter oxidation system is a volume of the exhaust manifold.

3. The system of claim 1, wherein the system includes a heating element for providing thermal energy to the particulate matter to convert the particulate matter from at least one of a solid and liquid phase to a gas phase gas capable of passing through the particulate filter.

4. The system of claim 1, wherein particulate matter is transported from the particulate filter to the particulate matter oxidation system via a non-thermal regeneration system.

5. The system of claim 1, wherein the system includes a valve for controlling flow out of the exhaust manifold into the settling tank.

6. The system of claim 1, wherein the system includes an oxidation catalyst coated to the particulate matter oxidation system.

7. The system of claim 3, wherein the system further includes a high porosity filter between the heating element and an exhaust pipe of the engine to trap and assist in oxidizing the particulate matter.

8. The system of claim 7, wherein the system further includes a second filter downstream from the high porosity filter for trapping ash and preventing the ash from reentering a main engine filter of the engine.

9. The system of claim 1, wherein the system further includes a valve for controlling flow of high temperature manifold gases for oxidizing the particulate matter.

10. The system of claim 1, wherein the system further includes an electric control module to control the flow of manifold gases into the particulate matter oxidation system.

11. A method for oxidizing particulate matter of an engine, the method comprising the steps of: introducing particulate matter into a particulate matter oxidation system for oxidizing particulate matter output from the engine; venting exhaust gases from an exhaust manifold in fluid communication with the particulate matter oxidation system into the particulate matter oxidation system to oxidize particulate matter produced by the engine; and filtering particulate matter from at least one of the engine and the particulate matter oxidation system via a particulate filter downstream from the particulate matter oxidation system.

12. The method of claim 11, wherein the particulate matter oxidation system is a volume of the exhaust manifold.

13. The method of claim 11, further including the step of providing thermal energy to the particulate matter via a heating element to convert the particulate matter from at least one of a solid and liquid phase to a gas phase gas capable of passing through the particulate filter.

14. The method of claim 11, wherein particulate matter is transported from the particulate filter to the particulate matter oxidation system via a non-thermal regeneration system.

15. The method of claim 11, further including the step of controlling flow out of the exhaust manifold into a settling tank via a valve.

16. The method of claim 11, wherein the particulate matter oxidation system includes an oxidation catalyst coated thereto.

17. The method of claim 13, wherein a high porosity filter is provided between the heating element and an exhaust pipe of the engine to trap and assist in oxidizing the particulate matter.

18. The method of claim 17, wherein a second filter is provided downstream from the high porosity filter for trapping ash and preventing the ash from reentering a main engine filter of the engine.

19. The method of claim 11, further including the step of controlling flow of high temperature manifold gases via a valve for oxidizing the particulate matter.

20. The method of claim 11, wherein an electric control module is provided to control the flow of manifold gases into the particulate matter oxidation system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings illustrate the best known mode of carrying out the present invention, including several embodiments of a particulate trap regeneration system incorporating the above advantages and in which:

[0024] FIG. 1 is a diagrammatic illustration prior art system for operating a lean burn diesel engine utilizing a passive and active thermal Diesel Particulate Filter (DPF) regeneration along with a Selective Catalytic Reduction (SCR) or Lean NOx Trap (LNT) for reducing the engine's NOx emissions;

[0025] FIG. 2 is a diagrammatic illustration of a first embodiment of a passive or passive/electrically active particulate matter oxidation system according to the teachings of the present invention;

[0026] FIG. 3 is a diagrammatic illustration of an external particulate matter oxidation system that traps particulate matter in a filter and oxidizes the particulate matter by flowing exhaust manifold gases out of the exhaust manifold and into a settling tank;

[0027] FIG. 4 is a diagrammatic illustration of a second embodiment of an external particulate matter oxidation system similar to the system illustrated in FIG. 3, and further including a valve for controlling flow out of the exhaust manifold into the settling tank;

[0028] FIG. 5 is a diagrammatic illustration of an additional embodiment similar to the systems illustrated in FIGS. 3 and 4, and further including the oxidation system attached to the engine's exhaust pipe;

[0029] FIG. 6 is a diagrammatic illustration of a system similar to the embodiment illustrated in FIG. 3, and further including a second filter for trapping ash;

[0030] FIG. 7 is a diagrammatic illustration of a system similar to the systems illustrated in FIGS. 3 and 6, and further including a valve to facilitate oxidization of the particulate matter in the first and second filter for trapping particulate matter and ash; and

[0031] FIG. 8 is a diagrammatic illustration of another system similar to the system illustrated in FIG. 4, wherein the system is constructed to function with vacuum, pressure, or any combination of the two regeneration methods.

DETAILED DESCRIPTION

[0032] FIG. 1 illustrates a prior art system for oxidizing particulate matter produced by a combustion engine. In the system illustrated in FIG. 1, a Selective Catalytic Reduction (SCR) or Lean NOx Trap (LNT) (either of which is referenced as numeral 32) is placed downstream of a diesel particulate filter (DPF) 28 for reducing the Nitrous Oxide (NOx) and Particulate Matter (PM) from a diesel engine 20 having an exhaust manifold 23 associated therewith.

[0033] In this known system, particulate matter is oxidized in the substrate (not illustrated) of DPF 28. Advanced, known injection timing produces NOx emissions with considerable NO, and after coming in contact with the expensive rare earth elements in Diesel Oxidation Catalyst (DOC) 24, is converted into NO2. Engine 20, DOC 24, PF 28, and SCR or LNT 32 are in fluid communication via an exhaust pipe 22 which exits from engine 20 and carries with it exhaust therefrom. A turbo 80 to provide a boost in output may also be included in the system illustrated in FIG. 1.

[0034] Because NO2 is less stable than NO and the temperature is above 250 Celsius, the NO2 will react with any stored soot in DPF 28, thus oxidizing particulate matter into CO2. If the operating temperature is below 250 Celsius, the particulate matter remains stored in DPF 28 and must be cleaned by many different thermal methods which could include, for example, late injection of fuel into the cylinder of engine 20 to increase the exhaust temperature above the 250 Celsius oxidation point condition for NO2 and over 500 Celsius for 02 oxidation. The time required for a complete regeneration may not ever be available, thus initiating warning lights and intervention by the operator.

[0035] As shown and illustrated in FIG. 1, urea 40 may be injected into exhaust emissions of the combustion engine via a urea injector 42 included in prior art systems upstream and/or downstream from DPF 28. FIG. 1 illustrates a urea injector 42 in locations both upstream and downstream from DPF 28.

[0036] FIG. 1 further illustrates various other known components long associated with engines such as engine 20 including: intake throttle valve 50 used during shutdown to keep engine 20 from shaking and throttling (e.g., reducing) air flow to the engine, exhaust gas recirculation (EGR) cooler 54 for reducing the Nitrogen Oxide (NOx) which causes acid rain and smog, clean up oxidation catalyst 60 which used if urea or Diesel Exhaust Fluid (DEF) is not used in reductant chemical reactions and allowed to exit the tailpipe, and an Exhaust Gas Recirculation (EGR) Valve as commonly known and understood in the art.

[0037] FIG. 2 is a diagrammatic illustration of a system for oxidizing particulate matter according to the teachings of the present invention. In a first embodiment, the system uses a porous volume, or particulate matter oxidation system (PMOS) 69 located within exhaust manifold 23. The volume can be either be a solid porous volume or have a porous outer shell. Non-thermal regeneration pressures from engine 20 may overcome valve 75, which could be a simple check valve to enter PMOS 69 within exhaust manifold 23. When this takes place, particulate matter exhaust gases and other components of exhaust enter the volume within exhaust manifold 23.

[0038] Exhaust manifold 23 preferably includes pressurized gases pulsating into the volume during blow down of the cylinders of engine 20, wherein the gases may be provided in a plurality of manners known in the art. In addition to the blow down of combustion gases, transient engine operation creates pressure in exhaust manifold 23, and increases and decreases the differential pressure and subsequent flow in and out of the porous volume. The flow of high temperature exhaust manifold gas preferably passively oxidizes the particulate matter within PMOS 69.

[0039] In some embodiments, the walls of PMOS 69 or its whole volume may be coated with an oxidation catalyst such as platinum to reduce the passive regeneration time. Other foreseeable catalysts known in the art besides platinum such as vanadium may also be used in certain embodiments. When vanadium is used, the catalyst is sulfur tolerant, and Platinum preferably generates NO.sub.2 from the NO available in the exhaust manifold gases.

[0040] Gases may subsequently reenter the exhaust stream before traveling through an SCR/DPF 30. Flow from exhaust pipe 22 to SCR/DPF 30 may be regulated by a valve 34, while flow from SCR/DPF 30 to an output may be regulated by a valve 36. Passing the manifold gases through the SCR/DPF 30 allows the NOx to be converted along with the rest of the exhaust stream.

[0041] Settling tank 39 including a valve associate therewith is preferably in fluid connection with exhaust pipe 22. Settling tank 39 is of the type known or foreseeable in the art for separating impurities from the various gases of the system.

[0042] In at least one alternative embodiment, urea could be directly injected into PMOS 69 or exhaust manifold 23. Such an embodiment allows for early urea injection, thus providing for low temperature operations and reducing corrosiveness of downstream components such as turbo 80.

[0043] FIG. 3 illustrates another embodiment in which exhaust manifold 23 and settling tank 39 are connected via PMOS 69. In the embodiment illustrated in FIG. 3, PMOS 69 traps particulate matter in a filter 70 and oxidizes the particulate matter by flowing exhaust manifold gases out of exhaust manifold 23 and into settling tank 39. Exhaust manifold gases are preferably released via exhaust manifold 23. This may be an important process during passive regeneration when the amount NOx entering and coming into contact with oxidation catalyst coated wire mesh or equivalent filter 70 will need to be varied.

[0044] A heating element such as heating element 78 may be used to help provide thermal energy to the particulate in order to convert the particulate matter from a solid and liquid phase to that of gas capable of passing through the particulate filter and SCR/DPF 30. It should be noted that the SCR/DPF 30 substrate could be a simple particulate filter catalyzed with an oxidation catalyst, selective catalytic reduction catalyst, or a simple uncatalyzed bare filter. Other foreseeable alternative substitutes are also contemplated herein.

[0045] FIG. 4 is a diagrammatic illustration of a second embodiment of an external particulate matter oxidation system similar to the system illustrated in FIG. 3, and further including a valve 79 that can either be a two position on/off valve or proportional for controlling flow out of exhaust manifold 23 into settling tank 39. Closing control valve 79 during peak accelerating conditions preferably increases or maximizes the exhaust and intake pressures (boost pressure), and subsequently the power output of engine 20.

[0046] FIG. 4 also includes an electronically controlled engine fitted with an Electronic Control Module (ECM) 90. ECM 90 may control valve 79 and variable geometry turbo 80 to further assist in controlling the flow of exhaust manifold gases into PMOS 69 while sensing and controlling the correct amount of exhaust flow through PMOS 69 to match the supplemental heating element 78 capabilities. During low load conditions where passive regeneration would not occur, thermal energy generated by heat element 78 assists in the direct oxidation of the particulate matter. In this manner, oxidation of the particulate matter can be achieved even with the engine at idle conditions.

[0047] Exhaust manifold gases may leave exhaust manifold 23 when valve 79 is open. When valve 79 is shut, the volume is pressurized by exhaust manifold 23. Flow similar to that of FIG. 2 provides pressurized exhaust gases flow in and out during transient operation. This transient flow allows passive regeneration even when flow to the settling tank 39 is unavailable due to engine performance requirements.

[0048] FIG. 5 is a diagrammatic illustration of an additional embodiment similar to FIGS. 3 and 4, but wherein PMOS 69 is attached to EGR piping 52 instead of attaching to exhaust manifold 23 of the oxidation system. Such a configuration allows the flexibility of the system to be retrofitted to older, legacy vehicles because the exhaust manifold would not have to be removed to fit the system to the vehicle. Also, servicing the piping is preferably improved.

[0049] FIG. 6 illustrates a system similar to FIGS. 3, 4, and 5. However, instead of the gases flowing through entire distance to the SCR/DPF combination 30 via the settling tank 39 and through valve 38, gases can be redirected into the exhaust stream near turbo 80. A first, high porosity filter 74 provided between heating element 78 and exhaust pipe 22 designed to trap and assist in oxidizing the particulate matter either with or without an oxidation catalyst and subsequent NO2 generation.

[0050] A second filter 76 for trapping ash and preventing it from reentering the main engine filter is placed downstream from filter 74 and is preferably a lower pore size filter with mean pore size levels smaller than or close to SCR/DPF combination 30. After oxidizing the particulate in filter 74, ash may pass through filter 74 before being captured in filter 76. The volume between filters 74, 76 is preferably large enough to hold the expected ash that can be accumulated for the life of the aftertreatment system. Alternatively, there could be any manner of volume between filters 74, 76 to create a volume and prevent filter 76 from plugging with ash. Filter 76 being in the vertical position with the ash volume directly below and out of the flow path is just one non-limiting example of a solution. While the system illustrates utilizes two filters for holding, oxidizing, and storing ash, in some embodiments, only one such filter is used.

[0051] FIG. 7 is a diagrammatic illustration of a system similar to the systems illustrated in FIGS. 3 and 6 but further including valve 79 to allow the pressurization of the particulate regeneration system utilizing a first high porosity filter 74 to oxidize the particulate matter in PMOS 69 and second filter 76 for trapping the ash from returning to the main engine filter. Valve 79 can replace or be used in addition to valve 72, the latter of which is illustrated in FIG. 7. Valve 79 operates substantially similarly to valve 79 in FIGS. 4 and 5 in that the closing of valve 79 would allow pressurization of the Particulate Matter Regeneration System (PRMS). In addition to the pressurization, back a forth flow from engine transient operation is preferably achieved.

[0052] FIG. 8 is a diagrammatic illustration of another embodiment of the present system similar to FIG. 4, but instead of pressurized non-thermal active regeneration system, the system can function with vacuum, pressure, or any combination of the two regeneration methods.

[0053] From the foregoing, it will be seen that the various embodiments of the present invention are well adapted to attain all the objectives and advantages hereinabove set forth together with still other advantages which are obvious and which are inherent to the present structures. It will be understood that certain features and sub-combinations of the present embodiments are of utility and may be employed without reference to other features and sub-combinations. Since many possible embodiments of the present invention may be made without departing from the spirit and scope of the present invention, it is also to be understood that all disclosures herein set forth or illustrated in the accompanying drawings are to be interpreted as illustrative only and not limiting. The various constructions described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts, principles and scope of the present invention.

[0054] Thus, there has been shown and described several embodiments of a novel system for oxidizing particulate matter using exhaust manifold gases. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms having and including and similar terms as used in the foregoing specification are used in the sense of optional or may include and not as required.

[0055] Many changes, modifications, variations and other uses and applications of the present constructions will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.