A heavy duty truck includes a diesel engine that generates an exhaust gas flow and an exhaust after-treatment system for treatment of the exhaust gas flow. The exhaust after-treatment system includes at least one temperature sensor at an underbody SCR system within the exhaust after-treatment system and a DEF injector upstream of a close-coupled SCR system within the exhaust after-treatment system. The DEF injector is operated to inject DEF into the exhaust gas flow at a rate that varies as a function of a temperature measured by the temperature sensor.

An exhaust aftertreatment system may include a reductant supply and diluent supply conduits, an injector and a control module. The reductant supply conduit includes a first valve controlling a flow of reductant through the reductant supply conduit. The diluent supply conduit includes a second valve controlling a flow of diluent through the diluent supply conduit. The injector is in fluid communication with the reductant supply conduit and the diluent supply conduit and is configured to provide fluid to an exhaust stream. The control module may control the first valve to provide a targeted amount of reductant through the injector. The control module may control the second valve to maintain a fluid flow rate through the injector that is at or above a minimum flow rate threshold of the injector based on a difference between a flow rate through the reductant supply conduit and the minimum flow rate threshold.

Selective catalytic reaction (SCR) failure detection systems and methods for propulsion systems. The method includes obtaining (a) an upstream (of the SCR unit) NO.sub.x concentration value, and (b) a downstream NO.sub.x concentration value, and caching (a) and (b). The obtaining and caching is repeated until N cached values are obtained, where N is a preprogrammed number. Using the N cached values, an upstream average of NO.sub.x, an upstream standard deviation, a downstream average of NO.sub.x, and a downstream standard deviation are calculated. The calculated values are input for a failure detection algorithm pertaining to nitrogen oxides (NO.sub.x) that generates a linear correlation factor. A best performing unacceptable (BPU) part is detected when the linear correlation factor is greater than a preprogrammed fail threshold.

A flow manifold system for injecting a first gas into a second gas, such as, for example, a system for injecting ammonia gas into the exhaust gas of an internal combustion engine. The first gas may be supplied to the system by one or more cartridges. The system may also include a control valve that is configured to control the delivery of the first gas to the least one critical flow orifice. The critical flow orifice is configured to allow for a relatively constant volumetric flow of the first gas through the critical flow orifice when the first gas attains a critical flow. Such critical flow may allow for an accurate estimation of the flow of the first gas through the critical orifice, and subsequently to the second gas, without the use of a flow sensor.

Selective catalytic reduction systems are known and are generally included in exhaust systems of diesel engines in order to treat the exhaust gases of such engines. Such systems involve the introduction of diesel exhaust fluid (DEF) into exhaust gas flowing in an exhaust passage of an engine. When dosing DEF onto a hydrolysis catalyst in a SCR system, the DEF will under certain conditions cool the hydrolysis catalyst sufficiently to either slow down or effectively prevent ammonia release, which creates a lag or delay in the function of the hydrolysis catalyst. This limits the amount of control which can be exerted over ammonia storage in the SCR catalyst, and NOx conversion. In a first step, a set of measurement data is received from one or more sensors provided in the system. Subsequently, a first set of characteristics associated with a state of a component of the catalytic system, a second set of characteristics associated with an output of the catalytic system and a third set of characteristics associated with a bias and a scaling factor in the system are derived. In a third step, the derived sets of characteristics are used to control the catalytic system.

A controller including a self-tuning circuit for controlling a pressure system to output an input pressure corresponding to an input pressure value using an adaptive fuzzy control system and updating dosing command values of a dosing command table for controlling a dosing unit of an aftertreatment system. The self-tuning circuit is configured to determine an input pressure value and generate a pressure control signal using the adaptive fuzzy control system based on the input pressure value, a detected input pressure, and an error amount. The self-tuning circuit is further configured to regulate the input pressure of reductant to the dosing unit from a reductant tank using a pressure control signal for a pressure control device. The self-tuning circuit is further configured to update a dosing command value of a dosing command table of the controller in conjunction with regulating the input pressure of reductant.

When an integrated value of a determination value correlated with a command value for an amount of supply of a reducing agent at the time of the command value being larger than a command supply amount threshold value reaches an integration threshold value, a determination is made that a diagnosis condition is satisfied, and an abnormality in the supply of the reducing agent is diagnosed based on an integrated value of the command value for the amount of supply of the reducing agent and an integrated value of an estimated value of the amount of supply of the reducing agent, whereas in cases where a period of time in which the diagnosis condition is not satisfied is longer than a time period threshold value, an interval of supply of the reducing agent is extended.

An internal combustion engine fluidly coupled to an exhaust aftertreatment system includes a particulate filter device, a first selective catalytic reduction device disposed upstream relative to a second selective catalytic reduction device, and an injection system disposed to inject a reductant into the exhaust gas feedstream upstream relative to the first selective catalytic reduction device. A method for controlling the internal combustion engine includes monitoring engine operation, and determining an amount of particulate matter stored on the particulate filter based thereon. An amount of reductant stored on the second selective catalytic reduction device and operating conditions associated with the exhaust aftertreatment system are also determined. A process to regenerate the particulate filter is executed only when the amount of reductant stored on the second selective catalytic reduction device is greater than a minimum threshold and the operating conditions are conducive to regenerating of the particulate filter.

A diesel exhaust fluid delivery system and a dual-variable control strategy for adjusting the delivery pressure and the mass flow rate of the fluid passing through the system. The method for operating the system using two operating modes: low flow rate and high flow rate. While operating in the low flow rate operating mode, the speed of a DEF pump remains constant and DEF delivery to the exhaust system is adjusted by controlling a backflow valve. While operating in the high flow rate operating mode, the backflow valve is closed and the speed of the pump is adjusted to regulate DEF delivery to the exhaust system.

A method for operating a delivery device for delivering a reducing agent from a reducing agent tank into an exhaust treatment device of an internal combustion engine of a motor vehicle, includes at least intermittently carrying out a ventilation process of the delivery device during operation of the internal combustion engine. A registration of a ventilation process first occurs. A timing unit having a preset time interval and/or a mass-flow summing unit having a preset total mass flow is then actuated. When the preset time interval and/or the preset total mass flow is reached, the ventilation process is then carried out. In particular, monitoring the delivery device by a pressure sensor can thus be omitted. A delivery device for delivering a reducing agent is also provided.