Abstract: Systems and methods are provided for determining and controlling an NO2 to NOx ratio reference target in an exhaust conduit between a first SCR catalyst and a second SCR catalyst. The method includes determining a present NO2 to NOx ratio in the exhaust conduit between the first SCR catalyst and the second SCR catalyst, and providing a reductant doser command in response to a deviation of the present NO2 to NOx ratio from the NO2 to NOx ratio reference target.

Abstract: A method includes determining a current mid-bed NH3 amount by operating an NH3 sensor positioned at a mid-bed location for an engine aftertreatment system having two SCR catalyst beds. The method further includes operating a NOx sensor positioned at the mid-bed location, and interpreting a current mid-bed ammonia to NOx ratio (ANR) and a current mid-bed NOx in response to the mid-bed NH3 amount and the operating the NOx sensor. The method further includes correcting an output value of the NOx sensor for cross-sensitivity to NH3. The method includes determining a mid-bed ANR constraint, determining a feedforward mid-bed NOx target, and providing a reductant injector command in response to the current mid-bed ANR, the current mid-bed NOx, the ANR constraint, and the feedforward mid-bed NOx target.

Abstract: An exemplary method includes determining an NH3 reference target in an exhaust conduit between a first SCR catalyst and a second SCR catalyst. The method includes determining a present amount of NH3 in the exhaust conduit between the first SCR catalyst and the second SCR catalyst, and determining an NH3 error term in response to the NH3 reference target and the present amount of NH3. The method further includes determining an amount of NOx downstream of the second SCR catalyst, and adjusting one of the NH3 reference target and a reductant doser command in response to the amount of NOx downstream of the second SCR catalyst. The method further includes providing a reductant doser command in response to the NH3 error term.

Abstract: A system includes an internal combustion engine, an exhaust conduit fluidly coupled to the internal combustion engine and an SCR catalyst, and a reductant doser operationally coupled to the exhaust conduit at a position upstream of the SCR catalyst. The reductant doser is responsive to a reductant doser command. The system includes a controller having a number of modules functionally structured to execute operations to compensate for transient operation of the system. An NH3 target module interprets a reductant amount target that is a target amount of reductant in the exhaust conduit at a position upstream of the SCR catalyst. A transient adjustment module detects a transient event in the SCR catalyst and provides an adjusted reductant amount target in response to the transient event and the reductant amount target. A dosing control module provides the reductant doser command in response to the adjusted reductant amount target.

Abstract: A method is disclosed for adjusting a target EGR mass flow in response to a current charge flow and target EGR fraction. The method includes interpreting an air-fuel ratio and a target air-fuel ratio. The method further includes interpreting a charge flow and a target EGR fraction. The method further includes determining an adjusted target EGR mass flow based on the air-fuel ratio, the target air-fuel ratio, the charge flow, and the target EGR fraction. The method further includes controlling an actuator based on the adjusted target EGR mass flow.

Abstract: A system includes an engine, an exhaust conduit for the engine, a first SCR catalyst fluidly coupled to the exhaust conduit, and a second SCR catalyst fluidly coupled to the exhaust conduit at a position downstream of the first SCR catalyst. The system further includes an ammonia sensor positioned between the first and second SCR catalysts. A reductant doser is positioned upstream of the first SCR catalyst. The system includes a controller that determines an amount of NH3 present from the NH3 sensor, and computes an actuator response function from at least one operating condition of the first SCR catalyst. The actuator response function includes a reductant injector response as a function of the amount of NH3, and the actuator response function includes a response discontinuity. The controller further determines a reductant injection amount from the amount of NH3 and the actuator response function, and provides a reductant injector command.

Abstract: A method includes determining whether selective catalytic reduction (SCR) test conditions are present, and in response to the SCR test conditions being present, operating an SCR aftertreatment system at a number of reduced ammonia to NOx ratio (ANR) operating points. The method further includes determining a deNOx efficiency value corresponding to each of the ANR operating points. The method further includes determining a reductant correction value in response to the deNOx efficiency values corresponding to each of the ANR operating points, and providing a reductant injection command in response to the reductant correction value.

Abstract: A method for controlling charge flow in an internal combustion engine includes operating an engine having a VGT. The method includes determining a target and current charge flow and EGR flow. The method further includes determining an error term for the charge flow and the EGR flow, and determining an exhaust pressure feedback command in response to the error terms. The exhaust pressure feedback command is combined with an exhaust pressure feedforward command, and the VGT is controlled in response to the exhaust pressure feedback command. The method additionally includes determining the exhaust pressure feedback command in response to a current EGR valve position. The method further includes controlling an EGR flow rate with the EGR valve at relatively closed EGR valve positions, and controlling the EGR flow rate with exhaust pressure at relatively open EGR valve positions.

Abstract: A fuel system has a fuel rail containing pressured fuel coupled to a plurality of fuel injectors. The system is operable in one embodiment to adjust fuel injector on-times by selecting one of the fuel injectors, determining a critical on-time for the selected injector corresponding to a minimum on-time duration to which the selected fuel injector is responsive to inject a discernable amount of fuel, generating an on-time for the selected fuel injector, determining an adjusted on-time for the selected fuel injector based on the generated on-time for the selected fuel injector, the critical on-time for the selected fuel injector and a reference critical on-time, and activating the selected fuel injector for the adjusted on-time to inject fuel into the engine. Alternatively or additionally, the adjusted on-time may be based on one or more estimated fuel injection quantities injected by the selected fuel injector.

Abstract: A method is disclosed for adjusting a target EGR mass flow in response to a current charge flow and target EGR fraction. The method includes interpreting an air-fuel ratio and a target air-fuel ratio. The method further includes interpreting a charge flow and a target EGR fraction. The method further includes determining an adjusted target EGR mass flow based on the air-fuel ratio, the target air-fuel ratio, the charge flow, and the target EGR fraction. The method further includes controlling an actuator based on the adjusted target EGR mass flow.

Abstract: A fuel system has a source of fuel coupled to a plurality of fuel injectors via a fuel rail. The system is operable to estimate a quantity of fuel injected into an internal combustion engine by disabling fuel flow from the source of fuel to the fuel rail, and monitoring a fuel request corresponding to a request for delivery of fuel by the fuel system to the engine produced by the engine. If the fuel request is below a threshold fueling level a selected fuel injector is controlled to inject a selected quantity of fuel from the fuel rail into the engine while inhibiting fuel injection the remaining fuel injectors, fuel rail pressure is sampled, a drop in the fuel rail pressure, resulting from injection of the selected quantity of fuel, is determined from the fuel rail pressure samples, and the quantity of fuel injected by the selected injector is determined as a function of the drop in fuel rail pressure.

Abstract: A fuel system has a source of fuel coupled to a plurality of fuel injectors via a fuel rail. The system is operable to determining a critical on-time for a selected one of the injectors by disabling fuel flow from the source of fuel to the fuel rail, periodically sampling fuel rail pressure, activating the selected injector for an on-time duration while inhibiting injection by remaining ones of the injectors, determining from the fuel rail pressure samples a pressure drop resulting from activation of the selected injector for the on-time duration, processing the pressure drop to determine whether or not the selected injector injected fuel, and repeatedly modifying the on-time duration followed by executing the sampling, activating, determining and processing steps until a critical on-time is determined that corresponds to a minimum on-time duration to which the selected fuel injector is responsive to inject a discernable amount of fuel.

Abstract: A fuel system has a fuel rail containing pressured fuel coupled to a plurality of fuel injectors. The system is operable in one embodiment to adjust fuel injector on-times by selecting one of the fuel injectors, determining a critical on-time for the selected injector corresponding to a minimum on-time duration to which the selected fuel injector is responsive to inject a discernable amount of fuel, generating an on-time for the selected fuel injector, determining an adjusted on-time for the selected fuel injector based on the generated on-time for the selected fuel injector, the critical on-time for the selected fuel injector and a reference critical on-time, and activating the selected fuel injector for the adjusted on-time to inject fuel into the engine. Alternatively or additionally, the adjusted on-time may be based on one or more estimated fuel injection quantities injected by the selected fuel injector.

Abstract: A fuel system has a source of fuel coupled to a plurality of fuel injectors via a fuel rail. The system is operable to determining a critical on-time for a selected one of the injectors by disabling fuel flow from the source of fuel to the fuel rail, periodically sampling fuel rail pressure, activating the selected injector for an on-time duration while inhibiting injection by remaining ones of the injectors, determining from the fuel rail pressure samples a pressure drop resulting from activation of the selected injector for the on-time duration, processing the pressure drop to determine whether or not the selected injector injected fuel, and repeatedly modifying the on-time duration followed by executing the sampling, activating, determining and processing steps until a critical on-time is determined that corresponds to a minimum on-time duration to which the selected fuel injector is responsive to inject a discernable amount of fuel.

Abstract: A fuel system has a source of fuel coupled to a plurality of fuel injectors via a fuel rail. The system is operable to estimate a quantity of fuel injected into an internal combustion engine by disabling fuel flow from the source of fuel to the fuel rail, and monitoring a fuel request corresponding to a request for delivery of fuel by the fuel system to the engine produced by the engine. If the fuel request is below a threshold fueling level a selected fuel injector is controlled to inject a selected quantity of fuel from the fuel rail into the engine while inhibiting fuel injection the remaining fuel injectors, fuel rail pressure is sampled, a drop in the fuel rail pressure, resulting from injection of the selected quantity of fuel, is determined from the fuel rail pressure samples, and the quantity of fuel injected by the selected injector is determined as a function of the drop in fuel rail pressure.

Abstract: A fuel system has a source of fuel coupled to a plurality of fuel injectors via a fuel rail. The system is operable to disable fuel flow to the fuel rail, select one of the fuel injectors to inject fuel into the engine while inhibiting fuel injection by the remaining fuel injectors, periodically sample fuel rail pressure, activate the selected fuel injector to inject fuel into the engine, determine from the fuel rail pressure samples a first value of the fuel rail pressure when the selected fuel injector is activated, deactivate the selected fuel injector, determine from the fuel rail pressure samples a second value of the fuel rail pressure when the selected fuel injector is deactivated, and compute a drop in pressure of the fuel rail due to injection of fuel by the selected fuel injector based on the first and second fuel rail pressure values.