Abstract:
One embodiment is a system including a controller operable to control fuel injection events. The system is operable in a base mode, and at least one of a deNOx mode, a deSOx mode, and a deSoot mode. The base mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, and a second post injection pulse. The deNOx mode includes a pilot injection pulse, a main injection pulse, and a post injection pulse. The deSOx mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, a second post injection pulse, and a third post injection pulse. The deSoot mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, a second post injection pulse, and a third post injection pulse. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Description:
CROSS REFERENCE 
       [0001]    This application claims the benefit of U.S. Application No. 60/876,221 filed Dec. 21, 2006, and the same is hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Diesel engines produce a number of combustion products including particulates, hydrocarbons (“HC”), carbon monoxide (“CO”), oxides of nitrogen (“NOx”), and oxides of sulfur (“SOx”). Future diesel engines will likely require exhaust aftertreatment systems to reduce emissions of these and other products of combustion. Such exhaust aftertreatment systems may include a number of components including catalytic conversion components, particulate filters, and others which can be operated in a variety of modes. In addition to base modes of operation, from time to time it may be necessary to implement regeneration modes which regenerate various components of exhaust aftertreatment systems. There is a need for apparatuses, systems and methods of flexible fuel injection in the foregoing and other modes. 
       SUMMARY 
       [0003]    One embodiment is a system including a controller operable to control fuel injection events. The system is operable in a base mode, and at least one of a deNOx mode, a deSOx mode, and a deSoot mode. The base mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, and a second post injection pulse. The deNOx mode includes a pilot injection pulse, a main injection pulse, and a post injection pulse. The deSOx mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, a second post injection pulse, and a third post injection pulse. The deSoot mode includes a pilot injection pulse, a main injection pulse, a post injection pulse, a second post injection pulse, and a third post injection pulse. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0004]      FIG. 1  is a schematic of an integrated engine-exhaust aftertreatment system provided in a vehicle. 
           [0005]      FIG. 2  is a schematic of an integrated engine-exhaust aftertreatment system operatively coupled with an engine control unit. 
           [0006]      FIG. 3  is a graph of fuel injection events according to a preferred base mode. 
           [0007]      FIG. 4  is a graph of fuel injection events a graph of fuel injection events according to a preferred deNOx regeneration mode. 
           [0008]      FIG. 5  is a graph of fuel injection events a graph of fuel injection events according to a preferred deSOx regeneration mode. 
           [0009]      FIG. 6  is a graph of fuel injection events a graph of fuel injection events according to a preferred deSoot regeneration mode. 
           [0010]      FIG. 7  is a graph showing lean and rich air/fuel ratios. 
           [0011]      FIG. 8  is a graph showing percent oxidation versus time for deSoot regeneration at various temperatures. 
       
    
    
     DETAILED DESCRIPTION  
       [0012]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated embodiments, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0013]    With reference to  FIG. 1 , there is illustrated a schematic of a preferred integrated engine-exhaust aftertreatment system  10  provided in a vehicle  7 . The aftertreatment subsystem  14  includes a diesel oxidation catalyst  16  which is preferably a close coupled catalyst but could be other types of catalyst units such as a semi-close coupled catalyst, a NOx adsorber or lean NOx trap  18 , and a diesel particulate filter  20  which are coupled in flow series to receive and treat exhaust output from engine  12 . 
         [0014]    The diesel oxidation catalyst unit  16  is preferably a flow through device that includes a honey-comb like substrate. The substrate has a surface area that includes a catalyst. As exhaust gas from the engine  12  traverses the catalyst, substances including CO, gaseous HC and liquid HC (unburned fuel and oil) are oxidized. As a result, these substances are converted to carbon dioxide and water. During operation, the diesel oxidation catalyst unit  16  is heated to a desired temperature value. 
         [0015]    The NOx adsorber  18  is operable to adsorb NOx and SOx emitted from engine  12  to reduce their emission into the atmosphere. The NOx adsorber  18  preferably includes catalyst sites which catalyze oxidation reactions and storage sites which store compounds. After NOx adsorber  18  reaches a certain storage capacity it is preferably regenerated through deNOx and/or deSOx processes. 
         [0016]    The diesel particulate filter  20  may include one or more of several types of particle filters. The diesel particulate filter  20  is utilized to capture unwanted diesel particulate matter from the flow of exhaust gas exiting the engine  12 . Diesel particulate matter includes sub-micron size particles found in diesel exhaust, including both solid and liquid particles, and may be classified into several fractions including: inorganic carbon (soot), organic fraction (often referred to as SOF or VOF), and sulfate fraction (hydrated sulfuric acid). The diesel particulate filter  20  may be regenerated by oxidizing the particulates trapped by the diesel particulate filter  20 . 
         [0017]    With reference to  FIG. 2 , there is illustrated a schematic of integrated engine-exhaust aftertreatment system  10  operatively coupled with an engine control unit (“ECU”)  28 . At least one temperature sensor  60  is connected with the diesel oxidation catalyst unit  16  for measuring the temperature of the exhaust gas as it enters the diesel oxidation catalyst unit  16 . In other embodiments, two temperature sensors  60  are used, one at the entrance or upstream from the diesel oxidation catalyst unit  16  and another at the exit or downstream from the diesel oxidation catalyst unit  60 . Information from temperature sensor(s)  60  is provided to ECU  28  and used to calculate the temperature of the diesel oxidation catalyst unit  16 . 
         [0018]    A first NOx temperature sensor  62  senses the temperature of flow entering or upstream of NOx adsorber  18  and provides a signal to ECU  28 . A second NOx temperature sensor  64  senses the temperature of flow exiting or downstream of NOx adsorber  18  and provides a signal to ECU  28 . NOx temperature sensors  62  and  64  are used to monitor the temperature of the flow of gas entering and exiting the NOx adsorber  18  and provide signals that are indicative of the temperature of the flow of exhaust gas to the ECU  28 . An algorithm may then be used by the ECU  28  to determine the operating temperature of the NOx adsorber  18 . 
         [0019]    A first universal exhaust gas oxygen (“UEGO”) sensor or lambda sensor  66  is positioned in fluid communication with the flow of exhaust gas entering or upstream from the NOx adsorber  18  and a second UEGO sensor  68  is positioned in fluid communication with the flow of exhaust gas exiting or downstream of the NOx adsorber  18 . The UEGO sensors  66 ,  68  are connected with the ECU  28  and generate electric signals that are indicative of the amount of oxygen contained in the flow of exhaust gas. The UEGO sensors  66 ,  68  allow the ECU  28  to accurately monitor air-fuel ratios (“AFR”) also over a wide range thereby allowing the ECU  28  to determine a lambda value associated with the exhaust gas entering and exiting the NOx adsorber  18 . 
         [0020]    Engine  12  includes a fuel injection system  90  that is operatively coupled to, and controlled by, the ECU  28 . Fuel injection system  90  delivers fuel into the cylinders of the engine  12 . Various types of fuel injection systems may be utilized in the present invention, including, but not limited to, pump-line-nozzle injection systems, unit injector and unit pump systems, common rail fuel injection systems and others. The timing of the fuel injection, the amount of fuel injected, the number and timing of injection pulses, are preferably controlled by fuel injection system  90  and/or ECU. 
         [0021]    ECU  28  executes software which includes a number of variables related to fuel injection. In a preferred embodiment the software utilizes some or all of the following variables: 
         [0022]    Cylinder_Fueling: The ultimate total fuel going into the cylinder. This variable is the summed quantity of all injections. 
         [0023]    Final Fuel: The fueling that comes out of the throttle position versus fueling table. 
         [0024]    Injected_Aux_Fuel: The total amount of fuel going in the injection event at the Aux_SOI timing. This variable includes feedforward fueling pulled out of the main injection and part or all of Catalyst Fuel. 
         [0025]    Injected_Aux 2 _Fuel: The total amount of fuel going in the injection event at the Aux 2 _SOI timing. This variable includes feedforward fueling pulled out of the main injection and part or all of Catalyst Fuel, and part or all of Catalyst Trim Fuel. 
         [0026]    Injected_Aux 3 _Fuel: The total amount of fuel going in the injection event at the Aux 3 _SOI timing. This variable includes part or all of Catalyst Trim Fuel. 
         [0027]    Catalyst Fuel: Extra amount of fuel for a regeneration event. This quantity can be split and put into the Aux and Aux 2  injection events. This variable is included in Cylinder_Fueling, but not Final Fuel. 
         [0028]    Catalyst Trim Fuel: Extra amount of fuel for a regeneration event. This variable is often closed loop feedback fuel, but can be feedforward from Regen tables. This variable can be split between Aux 2  and Aux 3  injection events. This variable is included in Cylinder_Fueling, but not Final Fuel. 
         [0029]    Injected_Pilot_Fuel: Fuel provided to a pre main injection pulse. This variable is included in Cylinder_Fueling and in Final Fuel. 
         [0030]    With reference to  FIGS. 3-6 , there are illustrated graphs fuel injection events for several preferred modes of operation. The X-axis of each of the illustrated graphs is piston position expressed in units of degrees after top dead center (“deg a TDC”). Thus, for example, an X-axis value of 0 (zero) indicates that piston position is at top dead center, an X-axis value of −10 indicates that piston position is 10 degrees before top dead center, and an X-axis value of 10 indicates that piston position is  10  degrees after top dead center. The Y-axis of each of the illustrated graphs is injected fueling volume in units of cubic millimeters (mm 3 ). The bars in each graph indicate injection pulses the timing of which is indicated by their X-axis position and the volume of which is indicated by of their Y-axis length. The legend in each of the illustrated graphs is a key which correlates the variables Catalyst Trim Fuel, Catalyst Fuel, and Final Fuel to the shaded portions of the injection pulses. 
         [0031]    With reference to  FIG. 3 , there is illustrated a graph of fuel injection events according to a preferred base mode or normal mode which is used for prime power and non-regenerative lean aftertreatment system operation. In the preferred base mode, the fuel injection events include main injection pulse  310 , pilot injection pulse  320 , post injection pulse  330 , and second post injection pulse  340 . Pilot injection pulse  320  and post injection pulse  330  are used for noise and emission control. Second post injection pulse  340  is used for catalyst temperature management. No fuel is provided by the Catalyst Fuel variable. The fuel provided by the Final Fuel variable is divided between main injection pulse  310 , pilot injection pulse  320 , and post injection pulse  330 . The fuel provided by the Catalyst Trim Fuel variable is provided at second post injection pulse  340 . 
         [0032]    With reference to  FIG. 4 , there is illustrated a graph of fuel injection events according to a preferred deNOx regeneration mode. In the preferred deNOx regeneration mode, the fuel injection events include main injection pulse  410 , pilot injection pulse  420 , and post injection pulse  430 . The Catalyst Fuel variable provides additional fuel at post injection pulse  430  as indicated by bracket  432 . This provides rich exhaust conditions to regenerate the NOx adsorber. The fuel provided by the Final Fuel variable is divided between main injection pulse  410 , pilot injection pulse  420 , and the portion of post injection pulse  430  indicated by bracket  431 . The quantity and timing of each of the fuel injection pulses provides transparency to the operator between the preferred base mode and the preferred deNOx regeneration mode. 
         [0033]    With reference to  FIG. 5 , there is illustrated a graph of fuel injection events according to a preferred deSOx regeneration mode. In the preferred deSOx regeneration mode, the fuel injection events include main injection pulse  510 , pilot injection pulse  520 , post injection pulse  530 , second post injection pulse  540 , and third post injection pulse  550 . The Catalyst Fuel variable provides additional fuel at post injection pulse  530  as indicated by bracket  532 . This provides rich exhaust conditions to regenerate trapped Sulfur compounds from the NOx adsorber. The fuel provided by the Catalyst Trim Fuel variable is divided between the portion of second post injection pulse  540  indicated by bracket  542 , and third post injection pulse  550 . The second and third post injection pulses provide temperature control during the deSOx regeneration. The fuel provided by the Final Fuel variable is divided between main injection pulse  510 , pilot injection pulse  520 , the portion of post injection pulse  530  indicated by bracket  531 , and the portion of post injection pulse  540  indicated by bracket  541 . The quantity and timing of each of the fuel injection pulses provides transparency to the operator between the preferred base mode and the preferred deSOx regeneration mode. 
         [0034]    With reference to  FIG. 6 , there is illustrated a graph of fuel injection events according to a preferred deSoot regeneration mode. In the preferred deSoot regeneration mode, the fuel injection events include main injection pulse  610 , pilot injection pulse  620 , post injection pulse  630 , second post injection pulse  640 , and third post injection pulse  650 . The Catalyst Fuel variable provides additional fuel at post injection pulse  630  as indicated by bracket  632 . This provides extra exhaust heat to combust soot in a soot filter such as a diesel particulate filter. The fuel provided by the Catalyst Trim Fuel variable is shared by second post injection pulse  640 , and third post injection pulse  650 . The second and third post injection pulses provide temperature control during deSoot regeneration. The quantity and timing of each of the fuel injection pulses provides transparency to the operator between the preferred base mode and the preferred deSoot regeneration mode. 
         [0035]    With reference to  FIG. 7 , there is illustrated a graph showing lean and rich exhaust air/fuel ratios. As shown in  FIG. 7 , the preferred lean air/fuel ratio is 20-55, the exhaust is 50-700 parts per million NOx, and temperature is 150 to 500° C. The preferred rich air/fuel ratio is 12-14. 
         [0036]    With reference to  FIG. 8 , there is illustrated a graph showing percent oxidation in a deSoot regeneration mode as a function of time for several temperatures. The X-axis shows time in units of hours, and the Y-axis shows percent soot oxidation. Curve  810  shows the percent soot oxidation over time at 360° C. Curve  820  shows the percent soot oxidation over time at 400° C. Curve  830  shows the percent soot oxidation over time at 500° C. Curve  840  shows the percent soot oxidation over time at 600° C. 
         [0037]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.