Patent Application
20110289906
The present disclosure generally relates to a system for treating exhaust gases. More particularly, a miniature regeneration unit for increasing an exhaust gas temperature is discussed.
In an attempt to reduce the quantity of NOx and particulate matter emitted to the atmosphere during internal combustion engine operation, a number of exhaust aftertreatment devices have been developed. A need for exhaust aftertreatment systems particularly arises when diesel combustion processes are implemented. Typical aftertreatment systems for diesel engine exhaust may include one or more of a diesel particulate filter (DPF), a selective catalytic reduction (SCR) system, a hydrocarbon (HC) injector, and a diesel oxidation catalyst (DOC).
During engine operation, the DPF traps soot emitted by the engine and reduces the emission of particulate matter (PM). Over time, the DPF becomes loaded and begins to clog. Periodic regeneration or oxidation of the trapped soot in the DPF is required for proper operation. To regenerate the DPF, relatively high exhaust temperatures in combination with an ample amount of oxygen in the exhaust stream are needed to oxidize the soot trapped in the filter.
The DOC is typically used to generate heat to regenerate the soot loaded DPF. When hydrocarbons (HC) are sprayed over the DOC at or above a specific light-off temperature, the HC will oxidize. This reaction is highly exothermic and the exhaust gases are heated during light-off. The heated exhaust gases are used to regenerate the DPF.
Under many engine operating conditions, however, the exhaust gas is not hot enough to achieve a DOC light-off temperature of approximately 300° C. As such, DPF regeneration does not passively occur. Furthermore, NOx adsorbers and selective catalytic reduction systems typically require a minimum exhaust temperature to properly operate.
A burner may be provided to heat the exhaust stream upstream of the various aftertreatment devices. Known burners have successfully increased the exhaust temperature of internal combustion engines for automotive use. Some Original Equipment Manufacturers have resisted implementation of prior burners due to their size and cost. Furthermore, other applications including diesel locomotives, stationary power plants, marine vessels and others may be equipped with relatively large diesel compression engines. The exhaust mass flow rate from the larger engines may be more than ten times the maximum flow rate typically provided to the burner. While it may be possible to increase the size of the burner to account for the increased exhaust mass flow rate, the cost, weight and packaging concerns associated with this solution may be unacceptable. Therefore, a need may exist in the art for a miniature regeneration unit to increase the temperature of the exhaust output from an engine while minimally affecting the cost, weight, size and performance of the exhaust system. It may also be desirable to minimally affect the pressure drop and/or back pressure associated with the use of a burner.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A system for controlling the temperature of an exhaust stream from an engine at a location upstream from an exhaust aftertreatment apparatus includes a main exhaust passageway adapted to receive the exhaust stream from the engine. A side branch is in communication with the main exhaust passageway. A regeneration unit is positioned within the side branch for combusting a fuel and heating the exhaust flowing through the main exhaust passageway. An ion sensor is operable to output a signal indicative of the presence of fuel combustion. A controller selectively operates the regeneration unit to increase the exhaust temperature. The controller is operable to control a supply of fuel to the regeneration unit based on the ion sensor signal.
A system is provided to control the temperature of an exhaust stream from an engine at a location upstream from an exhaust aftertreatment apparatus. The system includes a main exhaust passageway adapted to receive the exhaust stream from the engine. A blind side branch is in communication with the main exhaust passageway. A regeneration unit is positioned within the side branch for combusting a fuel and heating the exhaust flowing through the main exhaust passageway. The regeneration unit includes a housing positioned within and spaced apart from a sidewall of the side branch, a nozzle for injecting the fuel into a chamber defined by the housing, and an igniter to initiate combustion of the fuel within the housing. A controller selectively operates the regeneration unit to increase the exhaust temperature.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Exhaust aftertreatment system 10 also includes a miniature regeneration unit 26 positioned downstream from turbocharger 18 and upstream from a number of exhaust aftertreatment devices. In the exemplary aftertreatment system depicted in
Regeneration unit 26 is positioned within a side branch portion 34 of system 10 in communication with main exhaust passageway 14. Regeneration unit 26 may be used to heat the exhaust passing through passageway 14 to an elevated temperature that will enhance the efficiency of DOC 30 and allow regeneration of DPF 32.
Regeneration unit 26 may include one or more injectors 36 for injecting a suitable fuel and an oxygenator. The fuel may include hydrogen or a hydrocarbon. Injector 36 may be structured as a combined injector that injects both the fuel and oxygenator, as shown in
Regeneration unit 26 includes a housing 50 constructed as a multi-piece assembly of fabricated metal components. Housing 50 includes an inlet tube 52, a cylindrically-shaped body 54, and an outlet tube 56. An inlet header 58 is fixed to inlet tube 52. Inlet header 58 is fixed to side branch portion 34 and encloses one of its ends. Other single or multi-piece inlet assemblies are also contemplated as being within the scope of the present disclosure. An annular volume 62 exists in a space between an inner surface 64 of side branch portion 34 and an outer surface of housing 50.
An injector mount 65 is fixed to inlet tube 52 and/or inlet header 58 to provide an attachment mechanism for injector 36. A nozzle portion 66 of injector 36 extends into inlet tube 52 such that atomized fuel may be injected within a primary combustion chamber 68 at least partially defined by an inner cylindrical surface 70 of body 54. Injector 36 includes a fuel inlet 72 and an air inlet 74. Fuel inlet 72 is in communication with a fuel delivery system 76 including a fuel tank 78, a fuel filter 80, a fuel pump 82 and a fuel block 84 interconnected by a fuel line 86. Operation of the components of fuel delivery system 76 selectively provides hydrocarbon to injector 36.
A secondary air system 90 includes a secondary air filter 92 and a MAF sensor 94. A compressor 96 is in receipt of air that is passed through secondary air filter 92 and MAF sensor 94. Compressor 96 may include a portion of a supercharger, a turbocharger or a stand-alone electric compressor. Output from compressor 96 is provided to air inlet 74. When exhaust heating is desired, fuel is injected via fuel inlet 72 and the oxygenator is provided via air inlet 74 to inject a stream of atomized fuel. First igniter 42 is mounted to side branch portion 34 downstream of inlet header 58 and is operable to combust the fuel provided by injector 36 within primary combustion chamber 68.
Side branch portion 34 intersects exhaust passageway 14 at an angle A of substantially 30 degrees. The flame produced by regeneration unit 26 extends into exhaust passageway 14 at substantially the same angle.
An elongated aperture 110 extends through a pipe 112 defining main exhaust passageway 14. A portion of body 54 and outlet tube 56 are positioned within exhaust passageway 14. Exhaust provided from engine 12 impinges on housing 50 and cools it during operation of regeneration unit 26. Furthermore, because housing 50 minimally intrudes within passageway 14, exhaust back pressure is also minimally increased. It should also be appreciated that side branch portion 34 and injector 36 minimally radially outwardly extend from pipe 112. Such an arrangement allows an Original Equipment Manufacturer to more easily package the miniature regeneration unit on the vehicle.
In the present aftertreatment system, first igniter 42 also includes an ion sensor 44 coupled to a coil 46. Ion sensor 44 may be in the form of an electrode positioned within combustion chamber 68. A voltage may be applied to the ion sensor to create an electric field from the sensor to a ground such as housing 50. When voltage is applied, an electric field radiates from the sensor to the ground. If free ions are present in the field, a small ion current may flow. The magnitude of the ion current provides an indication of the density of the ions. Control module 38 detects and receives signals from ion sensor 44 to determine the presence or absence of a flame. Ion sensor 44 may also determine if igniter 42 is fouled.
Fouling may occur through deposition of soot, oil or other contaminants. When igniter 42 is fouled, proper combustion may not occur. Control module 38 is operable to supply and discontinue the supply of fuel to fuel inlet 72, air to air inlet 74 and electrical energy to igniter 42. Prior to initiating the supply of fuel and air to injector 36, control module 38 determines whether igniter 42 has been fouled via the signal provided by ion sensor 44. If the igniter is determined to be ready for operation, control module 38 may account for a number of engine and vehicle operating conditions such as engine speed, ambient temperature, vehicle speed, engine coolant temperature, oxygen content, mass air flow, pressure differential across diesel particulate filter 32, and any number of other vehicle parameters. If control module 38 determines that an increase in exhaust gas temperature is desired, fuel and secondary air are provided to injector 36. Coil 46 supplies electrical energy to igniter 42 to initiate combustion within primary combustion chamber 68.
Control module 38 may also evaluate a number of other parameters including presence of combustion and temperature of the exhaust gas within passageway 14 at a location downstream from regeneration unit 26 to determine when to cease the supply of fuel and air to injector 36. For example, control module 38 may receive signals from one or more temperature sensors located within regeneration unit 26, side branch portion 34 or within main passageway 14 to perform a closed loop control by operating regeneration unit 26 to maintain a desired temperature at a particular location. If combustion unexpectedly extinguishes, control module 38 ceases the supply of fuel. Other control schemes are also within the scope of the present disclosure.
Inlet tube 52e shown in
It is also contemplated that any one of the described miniature regeneration unit arrangements including apertures 150 may be equipped with an injector 36j having a relocated secondary air inlet 74j, to inject compressed air at a relatively low pressure into annular volume 62, as shown in
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application is a continuation-in-part of U.S. patent application Ser. No. 12/430,194, filed on Apr. 27, 2009. This application claims the benefit of U.S. Provisional Application No. 61/433,297 filed on Jan. 17, 2011. The entire disclosures of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61433297 | Jan 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12430194 | Apr 2009 | US |
| Child | 13197829 | US |
