Abstract:
Systems and associated methods of treating diesel exhaust in a vehicle are disclosed. An example method includes providing an exhaust aftertreatment device in an exhaust tailpipe, and a first nitrogen oxide (NOx) sensor upstream of the exhaust aftertreatment device, with the exhaust aftertreatment device configured to reduce NOx present in an exhaust flow through the exhaust aftertreatment device with a treatment fluid applied to the exhaust flow. This example method may also include measuring a concentration of NOx in the exhaust flow with the first sensor, determining an error in the measurement of the NOx concentration, and applying a learning corrective adjustment in a subsequent measurement of the NOx concentration in the exhaust flow in response to that determination. A first magnitude of the learning corrective adjustment may be based at least in part upon a second magnitude of the error in the measurement.
Abstract:
Technical solutions are described for an emissions control system for a motor vehicle including an internal combustion engine. An example computer-implemented method for controlling an exhaust system of an internal combustion engine, includes detecting a high hydrocarbon region in the operation of the internal combustion engine. The method further includes responsively, measuring an upstream temperature of an oxidation device of the exhaust system. Further yet, the method includes in response to the upstream temperature being equal to or above a predetermined threshold, delaying an O2 diagnosis of the exhaust system for a signal rationality delay time.
Abstract:
Selective catalytic reduction device (SCR) assessment methods include, while communicating exhaust to the SCR, determining a first temperature differential (dT) between a modeled exotherm phase temperature and a measured SCR exotherm outlet exhaust temperature, comparing the first dT to a first threshold, and determining that the SCR performance is suitable if the first dT is below the first threshold, or, if the first dT is above the first threshold, communicating exhaust gas to the SCR during a water endotherm phase, determining a second dT between a modeled endotherm phase temperature and a measured SCR endotherm phase outlet exhaust temperature, comparing the second dT to a second threshold, and determining that the SCR performance is suitable if the second dT is above the second threshold, or determining that the SCR performance is unsuitable if the second dT is below the second threshold. Performance can be SCR reductant storage capacity.
Abstract:
A selective catalytic reduction device (SCR) system performs intrusive steady state dosing correction (SSDC) when a NOx error between a predicted and measured downstream NOx value exceeds a threshold. In SSDC, if NOx breakthrough or NH3 slip is detected above a SSDC threshold, a short term reductant dosing adaptation occurs. Optionally long term dosing adaptations occur if the magnitude of previous short term adaptations exceed a short term adaptation threshold. If SSDC is insufficiently improving SCR performance based on the number of intrusive events occurring within a period of time and the change in NOx error during the time period, a method includes modifying the SSDC protocol by one or more of increasing the duration of short term adaptations, decreasing the SSDC threshold, and reducing the short term adaptation threshold. The method further includes subsequently inhibiting intrusive events from occurring.
Abstract:
Method for controlling and detecting ammonium nitrate and/or ammonium nitrite poisoning within selective catalytic reduction (SCR) devices and systems incorporating the same are provided. Methods can include detecting a SCR inlet exhaust gas NO2:NOx ratio above a poisoning NOx flux threshold, detecting a SCR temperature below a poisoning temperature threshold, and determining SCR catalyst poisoning. Methods can further include performing a SCR catalyst cleaning strategy, wherein the SCR cleaning strategy comprises heating the SCR catalyst composition to a temperature above the poisoning temperature threshold. Cleaning strategies can including utilizing a heater, implementing a post-injection, after-injection, and/or auxiliary injection engine strategy wherein the engine is configured to supply exhaust gas to the SCR. Methods can further include arresting reductant dosing, identifying an opportunistic regeneration opportunity, and/or inhibiting performance of an appurtenant oxidation catalyst subsequent to determining SCR catalyst poisoning. The SCR catalyst composition can comprise iron and/or copper.
Abstract:
Technical solutions are described for an emissions control system for a motor vehicle including an internal combustion engine. The emissions control system includes a selective catalytic reduction (SCR) device, an NOx sensor, and a controller for ammonia slip detection. The ammonia slip detection includes comparing an NOx measurement from the NOx sensor with a predicted NOx value. In response to the NOx measurement exceeding the predicted NOx value by a threshold value, the threshold value being calibrated to a first predetermined value, the threshold value is calibrated to a second predetermined value, a timer is initiated to a predetermined duration, and during the predetermined duration of the timer, in response to a second NOx measurement from the NOx sensor exceeding the predicted NOx value by the threshold value set to the second predetermined value, a reductant dosing rate of the SCR device is adapted according to the second predetermined value.
Abstract:
A vehicle includes an engine that combusts an air/fuel mixture to produce an exhaust gas stream containing oxides of nitrogen (NOx). A dosing system injects an amount of ammonia (NH3) into the exhaust gas stream based on an initial NH3 injection set point value. A selective catalyst reduction (SCR) device absorbs an amount of the NH3 contained in the exhaust gas stream and reduces an amount of NOx. An electronic hardware controller predicts an NH3 slip condition during which a portion the absorbed NH3 will slip from the SCR device, and modifies the initial NH3 injection set point value based on the predicted NH3 slip condition. The controller further generates a modified NH3 injection set point signal indicating an adjusted amount of the NH3 to inject during the predicted NH3 slip condition. The dosing system adjusts the amount of injected NH3 based on the modified NH3 injection set point signal.
Abstract:
A method to reduce NOx breakthrough and NH3 slip is provided when the SCR system is increasing in temperature and/or increasing exhaust gas mass flow. The method includes the steps of monitoring states of parameters of the exhaust gas upstream of an SCR catalyst where the states of parameters include at least one of the inlet temperature or the exhaust gas mass flow; identifying one of a temperature increase or an increased exhaust gas mass flow at the SCR inlet; identifying a new lower ammonia set-point or storage concentration for the SCR; and identifying the rate of NH3 consumption. The method further includes the step of determining an “intervening phase” a small dosage of DEF is continued during the intervening phase.
Abstract:
Embodiments of the invention include a method for performing diagnostics of a selective catalytic reduction (“SCR”) device in an exhaust gas treatment system of an internal combustion engine. The method includes monitoring an amount of sulfur in the SCR device of the exhaust treatment system and monitoring, by an SCR diagnostics module, an efficiency of the SCR device and indicating when the efficiency of the SCR device falls below an efficiency diagnostics threshold. Based on determining that the amount of sulfur in the SCR device is above a first threshold, the method includes disabling an operation of the SCR diagnostics module.
Abstract:
A method for reducing sensor noise in an automobile vehicle NOx sensor offset diagnostic includes: connecting an exhaust system to an engine of an automobile vehicle; sensing a condition of the exhaust system using at least one NOx sensor; identifying when the at least one NOx sensor is at a low noise condition; and running a diagnostic to identify conditions of the at least one NOx sensor. The method further includes selecting one of the low noise condition as the engine in an after-run condition or as the engine in an engine idle condition.