Abstract:
One embodiment is a method including maintaining a count based upon an engine operating condition, determining a soot level based upon a characteristic of a diesel particulate filter, and requesting deSoot based upon the count meeting or exceeding a threshold, or the soot level meeting or exceeding a threshold, or both. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Description:
PRIORITY 
     The benefits and rights of priority of U.S. Patent Application No. 60/876,289 filed Dec. 21, 2006 are claimed and that application is incorporated by reference. 
    
    
     BACKGROUND 
     Internal combustion engines including diesel engines produce a number of combustion products including particulates, hydrocarbons (“HC”), carbon monoxide (“CO”), oxides of nitrogen (“NOx”), oxides of sulfur (“SOx”) and others. Diesel particulate filters, such as catalyzed soot filters, close coupled catalysts and others can be used to trap particulates and reduce emissions from diesel exhaust. Such filters may undergo regeneration, or deSoot, to eliminate trapped diesel particulates. If a filter is allowed to load too much soot before regeneration, risks including filter overloading, uncontrolled regeneration, and filter failure may result. If soot regeneration occurs too frequently, unnecessarily thermal cycling and increased fuel penalty may result. There is a need for the unique and inventive soot filter regeneration software, systems, and methods disclosed herein. 
     SUMMARY 
     One embodiment is a method including maintaining a count based upon an engine operating condition, determining a soot level based upon a characteristic of a diesel particulate filter, and requesting deSoot based upon the count meeting or exceeding a threshold, or the soot level meeting or exceeding a threshold, or both. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic of an integrated engine-exhaust aftertreatment system provided in a vehicle. 
         FIG. 2  is a schematic of an integrated engine-exhaust aftertreatment system operatively coupled with an engine control unit. 
         FIG. 3  is a schematic of a preferred deSoot triggering control diagram. 
     
    
    
     DETAILED DESCRIPTION 
     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 that such further applications of the principles of the invention as illustrated therein as would normally occur to one skilled in the art to which the invention relates are contemplated and protected. 
     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 . 
     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, CO, gaseous HC and liquid HC (unburned fuel and oil) can be oxidized. During operation, the diesel oxidation catalyst unit  16  is heated to a desired temperature. 
     The adsorber  18  is preferably a NOx adsorber 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 can be regenerated through deNOx and/or deSOx processes. Other embodiments contemplate use of different NOx aftertreatment devices, for example, a converter such as a saline NOx catalyst. 
     The diesel particulate filter  20  is preferably a catalyzed soot filter, but may include one or more of several types of filters. The diesel particulate filter  20  can be utilized to capture 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 regeneration of diesel particulate filter  20  is referred to as deSoot or soot regeneration and may include oxidation of some or all of the trapped fractions of diesel particulate matter. The diesel particulate filter  20  preferably includes at least one catalyst to catalyze the oxidation of trapped particulate. 
     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  16 . Information from temperature sensor(s)  60  is provided to ECU  28  and used to calculate the temperature of the diesel oxidation catalyst unit  16 . 
     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 . 
     A first oxygen sensor  66  is positioned in fluid communication with the flow of exhaust gas entering or upstream from the NOx adsorber  18  and a second oxygen sensor  68  is positioned in fluid communication with the flow of exhaust gas exiting or downstream of the NOx adsorber  18 . Oxygen sensors are preferably universal exhaust gas oxygen sensors or lambda sensors, but could be any type of oxygen sensor. The oxygen sensors  66  and  68  are connected with the ECU  28  and provide electric signals that are indicative of the amount of oxygen contained in the flow of exhaust gas. The oxygen sensors  66  and  68  allow the ECU  28  to accurately monitor air-fuel ratios 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 . 
     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, high pressure common rail fuel injection 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  28 . 
     With reference to  FIG. 3 , there is illustrated a diagram  300  of a preferred deSoot triggering control which may be implemented as software, hardware or a combination thereof, and may be executed by an ECU, such as ECU  28 , or by another controller. Diagram  300  includes a fueling block  301  and a delta pressure block  302 . The output of fueling block  301  and the output of delta pressure block  302  are provided to conditional  350 . Conditional  350  is a Boolean OR operator which requests a deSoot operation when one or more of its inputs is true. The deSoot operation can be requested or commanded by using a deSoot request variable or flag  370 . If the output of conditional  350  is false, there will be no deSoot request as indicated by block  360 . It is also contemplated that additional inputs and logic networks may be connected to conditional  350 , for example, an enable or override input or logic network. 
     Fueling based block  301  includes block  310  which determines time since the last increment. The output of block  310  is provided to block  320  which determines a time multiplier based on an engine operating condition, for example, fueling. The output of block  320  is provided to block  330  which adds a new count to a counter. The counter will count (e.g., increment or decrement) at a base rate if the engine is in a first operation mode where the key switch on, and engine speed meets or exceeds a threshold. If the engine becomes air limited or is deNOx mode, then the counter will count at a faster rate than base rate to account for increased soot production during rich NOx regeneration. The counter will also count at an increased rate during rich SOx regeneration mode, which can account for the soot rate of production during deSOx regeneration. The counter value of block  330  is provided to conditional  340 , for example, by continuous, periodic, intermittent, or other types of interrogation of the counter value. Conditional  340  tests whether the counter count exceeds (or meets or exceeds) a threshold. The output of conditional  340  is provided to conditional  350  which can request or command deSoot as described above. 
     Delta pressure based block  302  includes conditional  311  which tests whether engine temperature exceeds (or meets or exceeds) an engine temperature threshold, and tests whether air flow exceeds (or meets or exceeds) an air flow threshold. If both thresholds have been exceeded (or met or exceeded) conditional  311  outputs true to block  321 . If one or both thresholds have not been exceeded (or met or exceeded) conditional  311  outputs false to block  312 . Block  321  calculates a soot level load based upon a pressure differential across a diesel particulate filter, or based upon an airflow rate across or through a diesel particulate filter, or preferably based upon both a pressure differential across a diesel particulate filter and an airflow rate across or through the filter or based upon combinations of these and other criteria. Block  321  provides the calculated soot level load to conditional  331  which tests whether the soot level load exceeds (or meets or exceeds) a soot level load threshold. The output of conditional  331  is provided to conditional  350  which can request deSoot as described above. The output of conditional  331  is also provided to block  341  which creates or maintains a count for soot filter cleaning. 
     As is evident from the figures and text presented above, a variety of embodiments according to the present invention are contemplated. Certain exemplary embodiments include a method comprising maintaining a count based upon an engine operating condition; determining a soot level based upon a characteristic of a diesel particulate filter; requesting deSoot based upon the count meeting or exceeding a threshold, or the soot level meeting or exceeding a threshold, or both. In further exemplary embodiments the determining a soot level based upon a characteristic of a diesel particulate filter includes determining a soot level based upon a pressure differential across a diesel particulate filter; the determining a soot level based upon a characteristic of a diesel particulate filter includes determining a soot level based upon an airflow rate across or through a diesel particulate filter; the determining a soot level based upon a characteristic of a diesel particulate filter includes determining a soot level based upon a pressure differential across the diesel particulate filter and an airflow rate of the diesel particulate filter; the maintaining a count based upon an engine operating condition includes incrementing or decrementing the count at a first rate if the engine speed exceeds a first threshold; the maintaining a count based upon an engine operating condition includes incrementing or decrementing the count at an increased rate if engine operation becomes air limited; the maintaining a count based upon an engine operating condition includes incrementing or decrementing the count at an increased rate if the engine is operating in a deNOx mode; the maintaining a count based upon an engine operating condition includes incrementing or decrementing the count at an increased rate if the engine is operating in a deSOx mode; and/or the maintaining a count based upon an engine operating condition includes incrementing or decrementing the count at a first rate if the engine speed exceeds a first threshold incrementing or decrementing the count at an increased rate if engine operation becomes air limited, the engine is operating in a deNOx mode, or the engine is operating in a deSOx mode. Further exemplary embodiments include determining if engine temperature meets or exceeds a threshold, or engine air flow meets or exceeds a threshold, or both; wherein said determining a soot level occurs only if engine temperature meets or exceeds a threshold, or engine air flow meets or exceeds a threshold, or both. 
     Certain exemplary embodiments include a system comprising a diesel particulate filter; a pressure sensor operable to sense a pressure of the diesel particulate filter; a processor operable to receive information of the pressure sensor; and a flow sensor operable to sense a flow of the diesel particulate filter; wherein the processor is operable to perform a first evaluation of a count and a count threshold, to perform a second evaluation of a soot load and a soot load threshold, and to instruct deSoot based upon the first evaluation or the second evaluation. In further exemplary embodiments the pressure sensor is operable to sense a pressure differential across the diesel particulate filter; the diesel particulate filter is a catalyzed soot filter; and/or the processor is a component of an ECU. Further exemplary embodiments include a diesel engine wherein the ECU is operatively coupled to the diesel engine; and/or a vehicle wherein the diesel engine is operatively coupled to the vehicle. 
     Certain exemplary embodiments include one or more computer readable media configured to store instructions to maintain a count, to store sensor information, and to command deSoot when a counter condition is satisfied or a sensor information condition is satisfied or both. Further exemplary embodiments include one or more computer readable media provided in an ECU. In further exemplary embodiments the counter condition includes a count exceeding a count threshold; and/or the sensor information condition includes delta pressure information and an air flow rate information. 
     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, more preferred or exemplary utilized in the description above indicate that the feature so described may be more desirable or characteristic, 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.