Provided is a method for controlling a vehicle exhaust gas treatment system, wherein the system includes an engine and a selective catalytic reduction device configured to receive exhaust gas from the engine and reductant from an injector. The method comprises determining a need for a reductant injection, determining a need for reductant injector noise abatement, and subsequently conducting one or more reductant injection events during one or more engine combustion events. A vehicle combustion event comprises combustion of fuel within a cylinder of the ICE. Determining a need for reductant injector noise abatement comprises determining if an engine speed is below a threshold, if a speed of the vehicle is below a threshold, if a decibel level of a vehicle audio system is below a threshold, or if a hands-free telephone system is being utilized by a passenger of the vehicle. The engine can be a diesel engine.

In an assembly and methods for NO.sub.x reductant dosing with variable spray angle nozzle, according to various embodiments, a reductant dosage is calculated. A reductant delivery region in an exhaust stream area of an aftertreatment system and an actuation period may be specified. Based at least on the reductant delivery region and the actuation period, the reductant insertion assembly may be placed in a state for reductant delivery such that one of a first array of reductant insertion ports and a second array of reductant insertion ports is in an open position. The shape of the variable spray angle nozzle may define different levels. Different arrays of reductant delivery ports may have varying operating characteristics, such as diameter, number of ports, actuation time, and/or reagent delivery angle and may be activated based on reductant flow pressure and/or reductant flow velocity.

A reductant delivery system includes an electronic control unit coupled with each of an electronically controlled reductant injector and an electronically controlled pump, and structured to mitigate obstruction of a reductant injector in an exhaust system of an engine. The electronic control unit is further structured to receive data indicative of a pump duty cycle, and calculate a diagnostic value based on pump duty cycle associated with injection of different amounts of reductant, compare the diagnostic value with a threshold value, and output an error signal to trigger an obstructed-injector mitigation action.

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.

An exhaust gas control apparatus includes a first catalyst, a filter, and an electronic control unit. The electronic control unit is configured to alternately execute lean control and rich control multiple times. The lean control is control for, over a period longer than a period from when a target air-fuel ratio is set to a predetermined lean air-fuel ratio until an air-fuel ratio of exhaust gas flowing out from the first catalyst becomes greater than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined lean air-fuel ratio. The rich control is control for, over a period longer than a period from when the target air-fuel ratio is set to a predetermined rich air-fuel ratio until the air-fuel ratio of exhaust gas flowing out from the first catalyst becomes smaller than the stoichiometric air-fuel ratio, setting the target air-fuel ratio to the predetermined rich air-fuel ratio.

A method for asynchronously delivering a reductant to a first selective catalytic reduction system and a second selective catalytic reduction system of an aftertreatment system via a reductant insertion assembly, the reductant insertion assembly comprising a first injector fluidly coupled to the first selective catalytic reduction system and a second injector fluidly coupled to the second selective catalytic reduction system, the method including: activating the first injector; maintaining the first injector activated for a first delivery time, thereby inserting a first amount of reductant into the first selective catalytic reduction system; deactivating the first injector; activating the second injector; and maintaining the second injector activated for a second delivery time, thereby inserting a second amount of reductant into the second selective catalytic reduction system.

An exhaust aftertreatment system includes a pump configured to circulate a reagent, an injector configured to deliver the reagent into an exhaust stream, a sensor configured to (i) measure an operating parameter of the aftertreatment system and (ii) output a signal that indicates a value of the measured operating parameter, and a control module configured to control the injector based on the signal outputted by the sensor. The control module includes a correction coefficient determination module configured to generate a correction coefficient based on the signal outputted by the sensor. The control module further includes an injector control module configured to receive an injector flow control signal, determine a pulse width modulation (PWM) signal based on at least the injector flow control signal, and generate an injector control signal that controls actuation of the injector based on at least the correction coefficient and the PWM signal.

A method is provided for controlling the injection, by a reductant injector in an exhaust system for an internal combustion engine, of reductant for an exhaust aftertreatment unit of the exhaust system, for example a selective catalytic reduction (SCR) unit. The method includes determining a reductant injection debt in dependence on a reductant flow according to at least a first request being higher than a threshold of the reductant flow, and, at least partly in dependence on the reductant injection debt, controlling the reductant injector so as to inject a compensation flow.

An abnormality determination device is used in an exhaust gas purification system. The exhaust gas purification system is disposed in an exhaust gas passage of an internal-combustion engine and includes an injection valve for injecting a liquid reducing agent to a NO.sub.x purification catalyst for purifying NO.sub.x in an exhaust gas, and a pump for pressurizing and supplying the reducing agent to the injection valve via a reducing agent passage. The abnormality determination device includes an acquisition section acquiring a rotation speed of the pump when the injection valve is injecting the reducing agent as an injection time rotation speed; and a determiner determining whether the injection valve has an abnormality based on the injection time rotation speed.

An aftertreatment system comprises an aftertreatment component structured to decompose constituents of an exhaust gas produced by an engine. A reductant insertion assembly is fluidly coupled to the aftertreatment component and configured to insert a reductant therein. A controller is operatively coupled to the reductant insertion assembly and configured to instruct the reductant insertion assembly to insert the reductant into the aftertreatment component for a first insertion time between first time intervals. The controller determines an operating condition of the engine, and determines if the operating condition satisfies a predetermined condition. In response to the predetermined condition being satisfied, the controller instructs the reductant insertion assembly to insert the reductant into the aftertreatment component for a second insertion time between second time intervals. The second insertion time is longer than the first insertion time.