Abstract:
One embodiment is a unique system for controlling EGR. Other embodiments include unique apparatuses, systems, devices, hardware, software, methods, and combinations of these and other techniques for controlling EGR.

Description:
PRIORITY 
       [0001]    The benefits and priority rights of U.S. Patent Application No. 60/876,777 filed Dec. 22, 2006 are claimed, and that application is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Internal combustion engines such as diesel engines may be provided with exhaust gas recirculation (“EGR”) systems which recirculate exhaust to the engine intake as well as exhaust aftertreatment systems which can be used to reduce or eliminate emissions such as particulates, hydrocarbons (“HC”), carbon monoxide (“CO”), oxides of nitrogen (“NOx”), oxides of sulfur (“SOx”), hydrogen-sulfide (“H 2 S”), and other emissions. EGR can aid in emissions control, for example, the mixing of recirculated exhaust gas and intake air can introduce dilutent effective to reduce combustion temperature, and reduce NOx formation and emissions. Under various operating conditions, for example, during engine startup, it may be desired to control EGR to facilitate engine operation compliant with a variety of conditions such as emissions, power output, torque output, horsepower output, and others. 
       SUMMARY 
       [0003]    One embodiment is a unique system for controlling EGR. Other embodiments include unique apparatuses, systems, devices, hardware, software, methods, and combinations of these and other techniques for controlling EGR. Further embodiments, forms, objects, features, advantages, aspects, and benefits of the present invention shall become apparent from the following illustrative description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0004]      FIG. 1  is a schematic illustration of system including a diesel engine, EGR and exhaust aftertreatment. 
           [0005]      FIG. 2  is a schematic illustration of a diesel engine and exhaust aftertreatment system. 
           [0006]      FIG. 3  is a schematic illustration of a diesel engine and EGR system. 
           [0007]      FIG. 4  is a schematic illustration of control logic. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the figures 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. 
         [0009]    With reference to  FIG. 1 , there is illustrated system  10  which includes an internal combustion engine  12  operatively coupled with an exhaust aftertreatment system  14 . Exhaust aftertreatment system  14  includes a diesel oxidation catalyst unit  16  which is preferably a close coupled catalyst but could be other types of catalyst units, an adsorber which is preferably a NOx adsorber or lean NOx trap  18  but could be other types of adsorbers or other NOx emissions control devices, and a diesel particulate filter  20 . The exhaust aftertreatment system  14  is operable to remove unwanted pollutants from exhaust gas exiting the engine  12  after combustion. 
         [0010]    The diesel oxidation catalyst unit  16  is preferably a flow through device that includes a canister that includes a honey-comb like structure or 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, pollutants may be converted to carbon dioxide and water. 
         [0011]    NOx adsorber  18  is operable to adsorb NOx and SOx emitted from engine  12  to reduce their emission into the atmosphere. NOx adsorber  18  includes catalyst sites which catalyzes oxidation reactions and storage sites which store compounds. After NOx adsorber  18  reaches a certain storage capacity it may be regenerated through one or more processes described as deNOx and/or deSOx. 
         [0012]    Diesel particulate filter  20  may include one or more of several types of particle filters. 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 may include sub-micron size particles found in diesel exhaust, including both solid and liquid particles, as well as fractions such as inorganic carbon (soot), organic fraction (often referred to as SOF or VOF), and sulfate fraction (hydrated sulfuric acid). Diesel particulate filter  20  may be regenerated at regular intervals by combusting particulates collected in diesel particulate filter  20 , for example, through temperature control achieved, for example, by control of EGR, fueling and/or turbocharger pressure boost. 
         [0013]    During engine operation, ambient air is inducted from the atmosphere and is preferably compressed by a compressor  22  of a turbocharger  23  most preferably a variable geometry turbocharger before being supplied to the engine  12 . The compressed air is supplied to the engine  12  through an intake manifold  24  that is connected with the engine  12 . An air intake throttle valve  26  may be positioned between the compressor  22  and the engine  12  that is operable to control the amount of charge air that reaches the engine  12  from the compressor  22 . The air intake throttle valve  26  may be connected with, and controlled by, an engine control unit (“ECU”)  28 , but may be controlled by other controllers as well. The air intake throttle valve  26  is operable to control the amount of charge air entering the intake manifold  24  via the compressor  22 . 
         [0014]    An air intake sensor  30  is included either before or after the compressor  22  to monitor the amount of ambient air or charge air being supplied to the intake manifold  24 . The air intake sensor  30  may be connected with the ECU  28  and may generate electric signals indicative of the amount or rate of air flow. An intake manifold pressure sensor  32  is connected with the intake manifold  24 . The intake manifold pressure sensor  32  is operative to sense the amount of air pressure in the intake manifold  24 , which is indicative of the amount of charge air flowing or provided to the engine  12 . The intake manifold pressure sensor  32  is connected with the ECU  28  and generates electric signals indicative of the pressure value that are sent to the ECU  28 . 
         [0015]    The system  10  may also include a fuel injection system  34  such as a high pressure common rail fuel system that is connected with, and controlled by, the ECU  28 . The fuel injection system  30  is preferably operable to deliver fuel into the cylinders of the engine  12 , while precisely controlling the timing of the fuel injection, fuel atomization, the amount of fuel injected, the number and timing of injection pulses, as well as other parameters. In certain embodiments stratified injection modes may be used. In other embodiments homogeneous, partial homogeneous and/or mixed injection modes may be used. Fuel is injected into the cylinders of the engine  12  through one or more fuel injectors  36  and is combusted, preferably by compression, with charge air and/or EGR received from the intake manifold  24 . Various types of fuel injection systems may be utilized in the present invention, including, but not limited to, pump-line-hozzle injection systems, unit injector and unit pump systems, common rail fuel injection systems and others. 
         [0016]    Exhaust gases produced in each cylinder during combustion leave the engine  12  through an exhaust manifold  38  connected with the engine  12 . A portion of the exhaust gas is communicated to an exhaust gas recirculation (“EGR”) system  40  and a portion of the exhaust gas is supplied to a turbine  42 . The turbocharger  23  is preferably a single variable geometry turbocharger  23 , but other types and/or numbers of turbochargers may be utilized as well. The EGR system  34  may be used to cool down the combustion process by providing a selectable amount of exhaust gas to the charge air being supplied by the compressor  22 . Cooling combustion may reduce the amount of NOx produced during combustion. One or more liquid, charge air, and/or other types of EGR coolers  41  may be included to further cool the exhaust gas before being supplied to the air intake manifold  22  in combination with the compressed air passing through the air intake throttle valve  26 . Furthermore, it is contemplated that high pressure loop EGR systems, low pressure loop EGR systems, and variations thereof could be used. 
         [0017]    EGR system  40  includes an EGR valve  44  in fluid communication with the outlet of the exhaust manifold  38  and the air intake manifold  24 . EGR valve  44  may also be connected to ECU  28 , which is capable of selectively opening and closing EGR valve  44 . EGR valve  44  may also have an associated differential pressure sensor that is operable to sense a pressure change, or delta pressure, across EGR valve  44 . A pressure signal  46  may also be sent to ECU  44  indicative of the change in pressure across EGR valve  44 . An air intake throttle valve  26  and EGR system  40 , in conjunction with fuel injection system  34 , may be controlled to run engine  12  in a rich mode or in a lean mode. 
         [0018]    The portion of the exhaust gas not communicated to the EGR system  40  is communicated to turbine  42  of a turbocharger, which is driven by gases flowing through the turbine  42 . Turbine  42  is connected to compressor  22  and provides driving force for compressor  22  which generates charge air supplied to the air intake manifold  24 . As exhaust gas leaves turbine  42 , it is directed to exhaust aftertreatment system  14 , where it is treated before exiting the system  10 . 
         [0019]    A cooling system  48  may be connected with the engine  12 . The cooling system  48  is preferably a liquid cooling system that transfers heat out of the block and other internal components of the engine  12 . The cooling system  48  includes a water pump, radiator or heat exchanger, water jacket (including coolant passages in the block and heads), and a thermostat which is operable to control the flow of coolant through the engine and through a radiator or by pass flow path. A coolant temperature sensor  50  is operable to generate a signal that is sent to ECU  28  indicative of the temperature of the coolant used to cool engine  12 . 
         [0020]    System  10  may include a doser  52  which may be located in the exhaust manifold  38  and/or located downstream of the exhaust manifold  38 . Doser  52  may comprise an injector mounted in an exhaust conduit  54 . For the illustrated embodiment, reductant or reducing agent introduced through the doser  52  is diesel fuel; however, other embodiments are contemplated in which one or more different reductant are used in addition to or in lieu of diesel fuel. Additionally, reductant could occur at a different location from that illustrated. Doser  52  is in fluid communication with a fuel line coupled to a source of fuel or other reductant (not shown) and is also connected with the ECU  28 , which controls operation of the doser  52 . Other embodiments omit or do not utilize a doser. For example, a preferred embodiment utilizes in-cylinder dosing where the timing and amount of fuel injected into the engine cylinders by fuel injectors is controlled in such a manner that engine  12  produces exhaust including a controlled amount of un-combusted (or incompletely combusted) fuel. Further embodiments may use a combination of in-cylinder dosing and dosing from a doser. 
         [0021]    System  10  also includes a number of sensors and sensing systems for providing ECU  28  with information relating to system  10 . An engine speed sensor  56  may be included in or associated with engine  12  and is connected with ECU  28 . Engine speed sensor  56  is operable to produce an engine speed signal indicative of engine rotation speed (“RPM”) that is provided to ECU  28 . A pressure sensor  58  may be connected with the exhaust conduit  54  for measuring the pressure of the exhaust before it enters the exhaust aftertreatment system  14 . Pressure sensor  58  may be connected with ECU  28 . If pressure becomes too high, this may indicate that a problem exists with the exhaust aftertreatment system  14 , which may be communicated to ECU  28 . 
         [0022]    At least one temperature sensor  60  may be 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 may be 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  or at other locations. These temperature sensors are used to calculate the temperature of the diesel oxidation catalyst unit  16 . In one embodiment, an average temperature may be determined, using an algorithm, from the two respective temperature readings of the temperature sensors  60  to arrive at an operating temperature of the diesel oxidation catalyst unit  16 . 
         [0023]    Referring to  FIG. 2 , a schematic diagram of exemplary exhaust aftertreatment system  14  is depicted connected in fluid communication with the flow of exhaust leaving the engine  12 . A first NOx temperature sensor  62  may be in fluid communication with the flow of exhaust gas before entering or upstream of the NOx adsorber  18  and is connected to ECU  28 . A second NOx temperature sensor  64  may be in fluid communication with the flow of exhaust gas exiting or downstream of the NOx adsorber  18  and is also connected to ECU  28 . NOx temperature sensors  62 ,  64  are used to monitor the temperature of the flow of gas entering and exiting NOx adsorber  18  and provide electric signals to ECU  28  which are indicative of the temperature of the flow of exhaust gas. An algorithm may then be used by ECU  28  to determine the operating temperature of NOx adsorber  18 . 
         [0024]    A first universal exhaust gas oxygen (“UEGO”) sensor or lambda sensor  66  may be positioned in fluid communication with the flow of exhaust gas entering or upstream from NOx adsorber  18  and a second UEGO sensor or lambda sensor  68  may be positioned in fluid communication with the flow of exhaust gas exiting or downstream of NOx adsorber  18 . Sensors  66 ,  68  are connected with ECU  28  and generate electric signals that are indicative of the amount of oxygen contained in the flow of exhaust gas. Sensors  66 ,  68  allow ECU  28  to accurately monitor air-fuel ratios (“AFR”) also over a wide range thereby allowing ECU  28  to determine a lambda value associated with the exhaust gas entering and exiting NOx adsorber  18 . 
         [0025]    Referring back to  FIG. 1 , an ambient pressure sensor  72  and an ambient temperature sensor  74  may be connected with ECU  28 . Ambient pressure sensor  72  is utilized to obtain an atmospheric pressure reading that is provided to ECU  28 . As elevation increases, there are fewer and fewer air molecules. Therefore, atmospheric pressure decreases with increasing altitude at a decreasing rate. Ambient temperature sensor  74  is utilized to provide ECU  28  with a reading indicative of the outside temperature or ambient temperature. As set forth in greater detail below, when engine  12  is operating outside of calibrated ambient conditions (i.e.—above or below sea level and at ambient temperatures outside of approximately 60-80° F.) the present invention may utilize a closed-loop control module to maintain the bed temperature of NOx adsorber  18  at the preferred regeneration temperature value (e.g. −650° C.). 
         [0026]    Referring to  FIG. 3 , an additional schematic of the system  10  is illustrated. The EGR system  40  includes the EGR valve  44  and the EGR cooler  41 . The EGR system  40  further includes an EGR cooler bypass valve  100  coupled to the EGR conduit  43  and flow coupled with an EGR cooler bypass conduit  102 . The EGR cooler  41  is flow coupled with an EGR cooler conduit  104 . The EGR cooler bypass valve  100  can be selectably positioned in a bypass or opened position, and a cooler or closed position. When the EGR cooler bypass valve  100  is in the bypass position some or all of the exhaust gas flowing through the EGR conduit  43  flows through the EGR cooler bypass conduit  103 . When the EGR cooler bypass valve  100  is in the cooler position all of the exhaust gas flowing through the EGR conduit  43  flows through the EGR cooler  41  to further cool the exhaust gas before being supplied to the air intake manifold  24  in combination with the compressed air passing through the air intake throttle valve  26 . In one embodiment, the EGR valve  44  is positioned downstream of both the EGR cooler conduit  104  and the EGR cooler bypass conduit  102 . In another embodiment, the EGR valve  44  is positioned upstream of both the EGR cooler conduit  104  and the EGR cooler bypass conduit  102 . In one embodiment of the present application, the EGR cooler bypass valve  100  is positionable in a mixed or partially opened position allowing at least a portion of the exhaust gas to flow through each of the EGR cooler bypass conduit  102  and the EGR cooler conduit  104 . 
         [0027]    Referring back to  FIG. 1 , at least one sensor  120  is connected with the engine  12  for measuring the temperature of intake or charge air of the engine  12 . In some embodiments sensor  120  may be an intake manifold temperature sensor. In some embodiments, sensor  120  may be a virtual intake manifold temperature sensor. In some embodiments sensor  120  may measure or virtually measure in cylinder temperature. In some embodiments sensor  120  may be upstream of intake manifold  24 , In further embodiments, two or more temperature sensors  120  may be used. The intake charge air temperature is sent from sensor  120  along with the coolant temperature from coolant temperature sensor  50  to the ECU  28 . In further embodiments, the location of the temperature measurement can be different or a virtual or estimated temperature can be used. As described in detailed below, the coolant and intake charge air temperatures are used by the ECU  28  in control of the EGR bypass valve  100 . 
         [0028]    Preferred embodiments contemplate NOx emissions control during the ensuing warm-up of the engine  12  from a cold start. A cold start typically means the engine  12  is started after achieving a soak temperature of approximately 70 degrees F. NOx emissions can be at least partially controlled by mixing exhaust gas with charge air from the compressor  22  in order to decrease the concentration of oxygen in the engine  12 . The end result is lower NOx emissions due to lower combustion temperatures. However, by reducing the concentration of oxygen in cylinders in the engine  12 , the likelihood of an engine misfire increases, particularly when the engine  12  is cold. Misfires may result when the charge oxygen concentration is insufficient (not enough ambient air) and/or when the charge temperature is too low to initiate or sustain combustion. To maximize the reduction of oxygen concentration while still avoiding misfire due to the engine being cold, the EGR cooler bypass valve  100  is operated in the bypass position. As discussed above, the exhaust gas in the EGR conduit  43  is routed around the EGR cooler  41  through the EGR cooler bypass conduit  102  when the EGR cooler bypass valve  100  is in the bypass position. By bypassing the EGR cooler  41 , the exhaust gas increases the charge temperature due to the mixing of uncooled recirculated exhaust gas, thus reducing the risk of an engine misfire. Once the engine reaches a predetermined state or condition, the EGR cooler bypass valve  100  returns to the cooler position and the recirculated exhaust gas passes through the EGR cooler  41 . The EGR valve bypass valve  100  is operably coupled to the ECU  28  to receive an operation signal  124  to move between the bypass position and the cooler position based on the predetermined state or condition. In one embodiment, the predetermined state is a combination of the intake charge air and the engine coolant temperatures. In another embodiment, the predetermined state includes only one of the coolant temperature and the intake charge air temperature. In one embodiment, the predetermined state includes a coolant temperature of about 120 degrees F. and an intake charge air temperature of about 140 degrees F. In another embodiment, the predetermined state includes a coolant temperature and an intake charge air temperature both at about 160 degrees F. The values provided for the intake charge air temperature and coolant temperature are exemplary values and the predetermined state maybe set based on desired operating conditions and it is within the scope of the present invention to include various temperature ranges for each of the intake charge air and the coolant temperatures. 
         [0029]    With reference to  FIG. 4 , there is illustrated a diagram of control logic operable to control the EGR cooler bypass valve such as EGR cooler bypass valve  100 . Variable  400  (the Engine_Speed variable) is provided to the x input of a lookup table  405 . Variable  400  is a function of engine speed and may be determined from a sensor such as engine speed sensor  56 . Variable  410  (the Total_Fueling variable) is provided to the y input of lookup table  405 . Variable  410  is a function of total fueling and may be determined by a sensor such as a virtual fueling sensor. Lookup table  405  outputs an intake manifold temperature high threshold based upon the inputs it receives. The output of lookup table  405  is provided to variable  450  (the H_ECBC_IMT_High_Threshold variable), which is a high threshold for intake manifold temperature, to the +input of operator  430 , and to operator  440 . Variable  460  is provided to the −input of operator  430 . Variable  460 , (the C_ECBC_IMT_HiToLow_Delta variable), is a delta or difference between the high threshold value of the intake manifold temperature and the low threshold value of the intake manifold temperature. Operator  430  subtracts the value of its bottom input from the value of its top input and outputs the result to operator  440  and to variable  470  (the H_ECBC_IMT_Low_Threshold variable) which is a low threshold for intake manifold temperature. Variable  480  (the IMT variable) is also input into the operator  440 . Variable  480  is a function of intake manifold temperature and in one embodiment is determined from a signal from the sensor  120 . 
         [0030]    Operator  440  determines whether intake manifold temperature is within the high intake manifold temperature threshold and the low intake manifold temperature threshold and outputs to operator  495  and to variable  490  (the H_ECBC_Position_Crnd_Cond1 variable). Variable  500  is provided to the top input of an operator  510 . Variable  500  is a function of coolant temperature, which can be determined based upon a signal from a sensor such as coolant temperature sensor  50 . Variable  520  is provided to the lower input of operator  510 . Variable  520  (the C_ECBC_Warmup_Collant_Tmptr variable) is a warm-up coolant temperature threshold or set point. Operator  510  determines if variable  500  is greater than or equal to variable  520  and outputs to operator  495  and to variable  530  (the H_ECBC_Position_CMD_Cond2 variable). Variable  490  is a first command condition variable and variable  530  is a second command condition variable. 
         [0031]    Operator  495  is a Boolean AND operator which outputs to variable  550  (the H_ECBC_Position_CMD variable), variable  540  (the ECBC_Position_State variable), and to operator  560  which is a Boolean NOT operator. Operator  560  outputs to variable  580  (the H_ECBC_Position_Cmd_Inv variable). Variable  580  is input into amplifier  570  which provides an amplified output to variable  590  and a variable  600 . In one embodiment, the amplifier  570  multiplies its input by fifty to drive current through the actuator of the cooler bypass valve  100 . Variable  590  is the H_ECBC_HB_Abs_DC variable and the signal  600  is the hb — 0_duty_cycle variable. 
         [0032]    In one embodiment, a controller, such as ECU  28 , commands or controls cooler bypass valve  100  in the opened or bypass position based upon the value of variable  540 . If variable  540  is a “1” (or on) the bypass mode is active and the cooler bypass valve  100  is open. If variable  540  is a “0” (or off) the bypass mode is inactive and the cooler bypass valve  100  is closed. In other embodiments, a controller, such as ECU  28 , may sets cooler bypass valve  100  in the closed position based upon the value of variable  540 . In further embodiments, a controller may also close the bypass valve  100  (or may close an EGR valve) when the Variable  480  (the IMT variable) exceeds a maximum threshold, such as variable  450  (the H_ECBC_IMT_High_Threshold variable), either in conjunction with or independent of coolant temperature. 
         [0033]    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.