Patent Abstract:
One embodiment is a unique method including determining a temperature of a NOx adsorber. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

Full Description:
PRIORITY 
     The benefits and rights of priority of U.S. patent application 60/876,778 filed Dec. 22, 2006 are claimed and that application is incorporated by reference. 
    
    
     BACKGROUND 
     Internal combustion engines such as 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 engines may by required to reduce or eliminate emission of these and other products of combustion, for example, by using one or more adsorbers, traps, catalytic components, and/or other components. When a component reaches a certain storage capacity it may be beneficial to perform regeneration. Regeneration to eliminate stored nitrogenous or nitrogen-containing compounds (NOx) is termed deNOx. Regeneration to eliminate stored sulfurous or sulfur-containing compounds (SOx) is termed deSOx. Regeneration to eliminate trapped particulates is termed deSoot. Regeneration activities are generally those through which a functionality of an exhaust aftertreatment component is restored or improved. Regeneration may require control of a variety of different operating conditions, for example, temperature, fueling, fresh air flow, and others. Unless adequate controls are provided, inefficient regenerations or regeneration failures may result. 
     SUMMARY 
     One embodiment is a unique method including determining a temperature of a NOx adsorber. 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 NOx adsorber bed temperature control diagram. 
         FIG. 4  is a NOx adsorber bed temperature control diagram. 
         FIG. 5  is a diagram of block  500  of  FIG. 3 . 
         FIG. 6  is a diagram of block  600  of  FIG. 3 . 
         FIG. 7  is a diagram of block  700  of  FIG. 3 . 
         FIG. 8  is a diagram of block  800  of  FIG. 4 . 
         FIG. 9  is a graph of fuel injection events. 
     
    
    
     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 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. 
     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) are oxidized. As a result, these pollutants are converted to carbon dioxide and water. During operation, the diesel oxidation catalyst unit  16  is heated to a desired temperature. 
     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 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 or soot filter  20  is preferably a catalyzed soot filter, but may be one or more of several additional or alternate 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, and 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 first temperature sensor  60 A 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 . A second temperature sensor  60 B measures temperature 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 sensors  60 A and/or  60 B is provided to ECU  28  and used to calculate the temperature of the diesel oxidation catalyst unit  16 . Additional temper sensor arrangements are contemplated including those having greater or fewer numbers of sensors, sensors positioned in different locations, virtual sensors, physical sensors and combinations of the foregoing and/or other alternatives. 
     A first NOx adsorber 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 . Additional temper sensor arrangements are contemplated including those having greater or fewer numbers of sensors, sensors positioned in different locations, virtual sensors, physical sensors and combinations of the foregoing and/or other alternatives. 
     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 generate 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 (“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 . 
     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 to 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 . An example of fuel injection parameters for one mode of operation is described below in connection with in  FIG. 9 . 
     Sensor  72  is operatively coupled with diesel particulate filter  20 . Sensor  72  is a pressure differential sensor which is operable to sense a pressure differential across diesel particulate filter  20  and provide pressure differential signal information to ECU  28 . Sensor  74  is a temperature sensor which is operable to sense a temperature at the outlet of diesel particulate filter  20  or downstream from diesel particulate filter  20  and provide temperature signal information to ECU  28 . ECU  28  can also receive temperature information from bed model virtual sensor  80 . ECU  28  can receive information about ambient or barometric pressure from sensor  80 . ECU  28  can receive information about fuel flow rate from fuel flow rate virtual sensor  82 . ECU  28  can receive information about fresh air flow rate from fresh air flow sensor  84 , which can be a mass flow rate sensor which is operatively coupled with a fresh air flow passage. Other sensor arrangements are also contemplated. 
     With reference to  FIG. 3 , there is illustrated a diagram of a preferred NOx adsorber bed temperature control  300 . NOx adsorber bed temperature control  300  receives variables  301 ,  302 ,  303 ,  304 ,  305 ,  306 ,  307 , and  308  as inputs. Variable  301  is NOx adsorber inlet temperature value which can be determined from a temperature sensor at the inlet to a NOx adsorber. Variable  302  is NOx adsorber outlet temperature value which can be determined from a temperature sensor at the outlet to a NOx adsorber. Variable  303  is injected aux 2  fuel which in one mode of operation is the fuel injection pulse  940  illustrated and described in connection with  FIG. 9 . Variable  304  is injected aux 3  fuel which in one mode of operation corresponds to the fuel provided by injection pulse  950  illustrated and described in connection with  FIG. 9 . Variable  305  is fresh air flow which can be determined from a fresh air flow sensor. Variable  306  is engine speed which can be determined from an engine speed sensor and is preferably filtered and further processed by an ECU. Variable  307  is a lambda value of the outlet of a NOx adsorber which can be determined from an oxygen sensor at the outlet of a NOx adsorber. Variable  308  is a lambda value of the inlet of a NOx adsorber which can be determined from an oxygen sensor at the inlet of a NOx adsorber. 
     Variables  301  and  302  are provided to block  500  which is described in further detail below in connection with  FIG. 5 . Variables  303 ,  304 ,  305 , and  306  are provided to block  600  which is described in further detail below in connection with  FIG. 6 . Variables  307  and  308  are provided to block  700  which is described in further detail below in connection with  FIG. 7 . Block  500  outputs an alternate NOx adsorber bed temperature reference value to variable  599  and to operator  360 . Block  600  outputs an alternate NOx adsorber bed temperature aux value to variable  699  and to operator  350 . Scaling variable  514  is also input to operator  350  which multiplies variable  514  and variable  699  and outputs to operator  360 . Block  700  outputs an alternate NOx adsorber bed temperature rich value to variable  799  and to operator  351 . Scaling variable  515  is also input to operator  351  which multiplies variable  515  and variable  799  and outputs to operator  360 . Operator  360  sums the values received at its inputs and outputs to variable  389  and operator  380 . Variable  389  is the unfiltered alternate NOx adsorber temperature value. Operator  380  is a filter that also receives variable  380  which is a filter constant and outputs to variable  399  the alternate NOx adsorber bed temperature value. 
     With reference to  FIG. 4 , there is illustrated a diagram of a preferred NOx adsorber bed temperature estimator  400 . Block  300 , the alternate NOx adsorber bed temperature model which was described above in connection with  FIG. 3 , and block  800 , the NOx adsorber bed temperature model which is described below in connection with  FIG. 8 , are provided to the top and bottom inputs of switch  410 , respectively. Alternate NOx adsorber temperature model enable variable  401  is provided to the switch input of switch  410  which outputs its top input when it receives a true value at its switch input and its bottom input when it receives a false value at its switch input. Switch  410  outputs to the bottom input of switch  420 . NOx bed sensor enable variable  402  is provided to the switch input of switch  420 . NOx adsorber outlet temperature value variable  302  is input to lookup table  415  which outputs a NOx adsorber bed temperature based upon the input value it receives. 
     The output of lookup table  415  is provided to the top input of switch  420  which outputs its top input when it receives a true value at its switch input and its bottom input when it receives a false value at its switch input. Switch  420  outputs to variable  489  which is a first NOx adsorber bed temperature value and to the bottom input of switch  430 . NOx bed user value variable  427  is provided to the top input of switch  430  and NOx bed user enable variable  428  is provided to the switch input of switch  430  which outputs its top input when it receives a true value at its switch input and its bottom input when it receives a false value at its switch input. The output of switch  430  is provided to variable  499  which is a second NOx adsorber bed temperature value. 
     With reference to  FIG. 5 , there is illustrated a diagram of block  500  of  FIG. 3 . Block  500  receives variables  301  and  302  which were described above. Block  500  also receives variable  501  which is the alternate NOx adsorber bed temperature T 1  basis. Variable  301  and variable  501  are input to operator  520  which multiplies its inputs and outputs to operator  540 . Variable  510  and variable  509  (which is a constant set=1 in the illustrated embodiment) are input to operator  510  which subtracts variable  509  from variable  501  and outputs to operator  530 . Variable  302  is also provided to variable  530  which multiplies its inputs and outputs to operator  540 . Operator  540  sums its inputs and outputs to variable  599 . 
     With reference to  FIG. 6 , there is illustrated a diagram of block  600  of  FIG. 3 . Block  600  receives variables  303 ,  304  and  305  which were described above. Block  600  also receives variables  603  which is a filter constant, variable  605  which is a number of cylinders value, variable  606  which is set to a constant value of 17793 in the illustrated embodiment, variable  607  which is set to a constant value of 60 in the illustrated embodiment in order to convert between hours and minutes, variable  623  which is an alternate NOx bed temperature aux 2  scaling value, and variable  633  which is a an alternate NOx bed temperature aux 3  scaling value. 
     Variables  303  and  603  are input to filter  613  which filters variable  303  and outputs to operator  620 . Variables  304  and  603  are input to filter  610  which filters variable  304  and outputs to operator  630 . Variable  605 ,  606  and  607  are input to operators  620  and to operator  630 . Operator  610  multiplies the output of filter  613  by variable  605  and variable  306 , divides the result by variable  606  and variable  607 , and outputs to variable  622  which is an aux 2  fuel rate and operator  625 . Operator  620  multiplies the output of filter  610  by variable  605  and variable  306 , divides the result by variable  606  and variable  607 , and outputs to variable  632  which is an aux 3  fuel rate and operator  635 . Operator  625  multiplies variable  622  and variable  623  and outputs to operator  640 . Operator  635  multiplies variable  632  and variable  6323  and outputs to operator  640 . Operator  640  sums its inputs and outputs to operator  640 . 
     Variable  305  is input to operator  649  as is variable  647  which is set to a constant of 0.5 in the illustrated embodiment. Operator  640  takes the maximum of its inputs and outputs to operator  650 . Operator  650  divides the output of operator  640  by the output of operator  649  and outputs to variable  699 , the alternate NOx bed temperature Saux value. 
     With reference to  FIG. 7 , there is illustrated a diagram of block  700  of  FIG. 3 . Block  700  receives variables  307  and  307  which were described above. Block  700  also receives variables  701  which is the alternate NOx bed temperature lambda threshold, variable  702  which is set as a constant=1 in the illustrated embodiment, and variable  703  which provides divide by zero protection. Variable  307  is provided to operators  710  and  712 . Variable  308  is provided to operators  711  and  713 . Variable  701  is provided to operators  710  and  711 . Constant  703  is provided to operators  712  and  713 . Constant  702  is provided to operators  721  and  722 . 
     Operator  710  evaluates whether variable  307 &gt;=variable  701  and outputs to operator  720 . Operator  711  evaluates whether variable  308 &gt;=variable  701  and outputs to operator  720 . Operator  720  is a Boolean OR operator which outputs to the switch input of switch  730 . Operator  712  outputs the maximum of its inputs to operator  721 . Operator  713  outputs the maximum of its inputs to operator  722 . Operator  721  divides its top input by its bottom input and outputs to operator  725 . Operator  722  divides its top input by its bottom input and outputs to operator  725 . Operator  725  subtracts its bottom input from its top input and outputs to operator  729 . Operator  729  outputs to the bottom input of switch  730 . Constant  706  which is set equal to zero in the illustrated embodiment is provided to the top input of switch  730 . Switch  730  outputs its top input when the value provided to its switch input is true and outputs its bottom input when the value provided to its switch input is false. Switch  730  outputs to variable  799 . 
     With reference to  FIG. 8 , there is illustrated a diagram of block  800  of  FIG. 4 . Catalyst Fuel variable  801 , Injected_Aux 2 _Fuel variable  802 , and Injected_Aux 3 _Fuel variable  803  are input to operator  820  which sums its inputs and outputs to filter  821 . Filter constant  804  is also provided to filter  821  which filters the input it receives from operator  820  and outputs to variable  822  and to operator  823 . Number of cylinders variable  816  filtered engine speed variable  817 , constant  826  which converts between hours and seconds, constant  826  which converts between kilograms and pounds, and constant  825  are also input to operator  823 . Operator  823  multiplies variables  822 ,  816 ,  817 , and constant  826  and divides by constants  824  and  825 , and provides its output to variable  827 , operator  828  and operator  829 . Operator  828  tests whether variable  827 &gt;constant  838  and outputs to the switch input of switch  830 . 
     Turbine outlet temperature value variable  805  is input to Fahrenheit to Kelvin converter which outputs to variable  888  and to operator  844 . Fresh air flow variable  806 , pounds to kilograms conversion constant  807 , minutes to second conversion constant  808 , and variable  809  are input to operator  822 . Operator  822  multiplies variable  806 , constant  807  and variable  808 , divides by constant  808 , and outputs to operators  844 , flag  845  and operator  846 . Operator  844  multiplies its inputs and outputs to variable  841  and operator  840 . NOx adsorber input temperature variable  810  and ccc offset variable  811  are provided to operator  823  which sums its inputs and outputs to variable  877  and operator  846 . Operator  846  outputs to variable  843  and operator  840 . Variable  842  is also provided to operator  840 . 
     Operator  840  adds its bottom two inputs and subtracts its top input and outputs to operator  829 . Constant  839  is also provided to operator  829 . Operator  829  divides by its top two inputs, multiplies by its bottom input, and outputs to the top input of switch  830 . Constant  837  is provided to the bottom input of switch  830 . Switch  830  outputs to variable  831  and operator  832 . Constant  836  is also provided to operator  832 . Operator  832  subtracts its top input from its bottom input and outputs to operator  833 . Variable  853  is also provided to operator  833  which multiplies its inputs and outputs to variable  834 . 
     NOx adsorber outlet temperature variable  818  and NOx adsorber inlet temperature variable  819  are provided to operator  847  which subtracts its bottom input from its top input and outputs to variable  848  and operators  886 ,  885  and lookup table  853 . Operators  886 ,  885 ,  883  and  884  perform debounce and output to filter  855  which also receives filter constant  858 . Filter  855  outputs to lookup table  853  and variable  852 . Lookup table  853  outputs to variable  851  and operator  849 . Operator  849  multiplies its inputs and outputs to variable  850 . 
     NOx adsorber inlet temperature variable  813  and variable  814  are input to operator  864  which multiplies its inputs and outputs to variable  863  and operator  862 . Variable  815  is also provided to operator  862  which sums its inputs and outputs to operator  860 . Variable  861  is also provided to operator  860  which divides its top input by its bottom input and outputs to variable  859  and filter  857 . Variable  814  inputs to lookup table  865  which outputs to lookup table  866  and variable  867 . Lookup table  866  outputs to filter  857 . Filter  857  outputs to variable  899 , which can be provided to the output of block  400  as illustrated above in connection with  FIG. 4 . 
     With reference to  FIG. 9 , there is illustrated a graph of fuel injection events  900  according to a preferred deSoot regeneration mode. The X-axis of each of graph  900  is piston position expressed in units of degrees after top dead center (“deg aTDC”). 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 graph  900  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. Additionally, the following terms relate to  FIG. 9 : 
     Cylinder_Fueling: The ultimate total fuel going into the cylinder. This variable is the summed quantity of all injections. 
     Final Fuel: The fueling that comes out of the throttle position versus fueling table. 
     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. 
     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. 
     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. 
     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. 
     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. 
     Injected_Pilot_Fuel: Fuel provided to a pre main injection pulse. This variable is included in Cylinder_Fueling and in Final Fuel. 
     The fuel injection events include main injection pulse  910 , pilot injection pulse  920 , post injection pulse  930 , second post injection pulse  940 , and third post injection pulse  950 . The Catalyst Fuel variable provides additional fuel at post injection pulse  930  as indicated by bracket  932 . 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  940 , and third post injection pulse  950 . 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. 
     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, 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. There is no desire to limit an claim to a particular embodiment, mode, characteristic, criteria of the foregoing embodiments other than as recited by the following claims.

Technology Classification (CPC): 5