A selective catalytic reduction system includes a reducing agent injection module installed in an exhaust pipe through which an exhaust gas is discharged from an engine and configured to inject a reducing agent into the exhaust pipe, a temperature calculator configured to calculate a temperature of the reducing agent injection module using temperature-related information of the reducing agent injection module, and a temperature controller configured to control to increase a reducing agent injection amount of the reducing agent injection module when the calculated temperature.

An exhaust gas purification system and an exhaust gas purification method are disclosed. The exhaust gas purification system is provided with: an injector for injecting urea water, said injector being installed between a combustion device and a selective catalytic reduction (SCR) catalyst; a first gas sensor which is installed downstream of the SCR catalyst, and which detects the NO concentration and the NH.sub.3 concentration in exhaust gas outputted from the SCR catalyst; and an opening amount control means for controlling the opening amount of the injector for injecting urea water.

A controller includes a switching delay circuit structured to determine an open delay time and a close delay time for a reductant injector, each based on battery voltage and reductant injector coil temperature. A dosing circuit is structured to determine an open time that the armature pin must be in the fully open position so as to cause the injector to inject a first quantity of reductant. An actuation time is determined based on each of the open time, the open delay time, and the close delay time. The actuation time relates to a time that the coil must be energized so as to cause the injector to inject the first quantity of reductant. A switching command signal is transmitted to the injector to energize the coil for the calculated actuation time so as to cause the injector to inject the first quantity of reductant into an exhaust gas stream.

A urea SCR system includes a tank that stores urea water, an injector that injects urea water to exhaust gas, a connection passage that connects the tank and the injector, an electric pump that is arranged at the connection passage and delivers urea water from the tank toward the injector or from the injector toward the tank, and a control device that controls the electric pump and the injector. The control device executes a suction-back operation for driving the electric pump so that urea water contained in the injector is suctioned back to the tank. Further, the control device determines whether or not the injector is stuck closed.

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.

An exhaust purification device of an engine includes: an exhaust passage; a urea injector supplying urea water into the exhaust passage; a pump device which supplies urea water stored in a urea tank to the urea injector, the pump device capable of performing an operation of recovering the urea water supplied to the urea injector to the urea tank; an SCR catalyst which purifies the exhaust gas using urea; and a controller. The controller controls the pump device such that the supply of the urea water to the urea injector is stopped, and a recovery operation for recovering the urea water in the urea injector to the urea tank is performed in a case where an amount of ammonium adsorbed by the SCR catalyst is larger than a predetermined reference adsorption amount under a condition where an internal temperature of the urea injector reaches a predetermined high temperature.

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.

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.

In an exhaust gas control system for an internal combustion engine, addition valves which add an additive toward a first selective reduction NOx catalyst are provided in an exhaust passage on both of an upstream side and a downstream side of the SCR catalyst. In a case where a flow rate of exhaust gas flowing in the exhaust passage is equal to or lower than a predetermined flow rate, the additive is added from both addition valves to allow ammonia to be adsorbed onto the first selective reduction NOx catalyst.

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.