A control device for an internal combustion engine including an upstream cleaning device and a downstream cleaning device that are provided in an exhaust gas passage and a temperature sensor that detects a temperature of exhaust gas between the upstream cleaning device and the downstream cleaning device is provided. The control device includes a first temperature estimating unit configured to estimate a temperature of the downstream cleaning device from the temperature of exhaust gas detected by the temperature sensor and a second temperature estimating unit configured to estimate a temperature of the downstream cleaning device without using the temperature of exhaust gas detected by the temperature sensor. An abnormality determining process for the upstream cleaning device is performed when at least the temperature of the downstream cleaning device estimated by the second temperature estimating unit is equal to or greater than a predetermined threshold value.

Methods and systems to control a temperature of a selective catalytic reduction catalyst are disclosed. In one example, a diverter valve that includes two butterfly valves that are coupled together via a shaft is adjusted to control a temperature at an inlet of the selective catalytic reduction catalyst so that the selective catalytic reduction catalyst may operate efficiently.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

An exhaust aftertreatment system and associated system for purifying an exhaust gas feedstream of a lean-burn engine includes an oxidation catalyst that is arranged upstream of a selective catalytic reduction (SCR) catalyst. A first NOx sensor is arranged upstream, and a second NOx sensor is arranged downstream of the oxidation catalyst. A controller is arranged to monitor the oxidation catalyst based upon inputs from the first and second NOx sensors. A first NOx parameter is determined via the first NOx sensor, and a second NOx parameter is determined via the second NOx sensor. An NO2 parameter is determined based upon the first NOx parameter, the second NOx parameter, a first relationship for the first and second NOx sensors, and a second relationship for the first and second NOx sensors. The NO2 production of the oxidation catalyst is evaluated based upon the NO2 parameter.

A control device for an internal combustion engine including an upstream cleaning device and a downstream cleaning device that are provided in an exhaust gas passage and a temperature sensor that detects a temperature of exhaust gas between the upstream cleaning device and the downstream cleaning device is provided. The control device includes a first temperature estimating unit configured to estimate a temperature of the downstream cleaning device from the temperature of exhaust gas detected by the temperature sensor and a second temperature estimating unit configured to estimate a temperature of the downstream cleaning device without using the temperature of exhaust gas detected by the temperature sensor. An abnormality determining process for the upstream cleaning device is performed when at least the temperature of the downstream cleaning device estimated by the second temperature estimating unit is equal to or greater than a predetermined threshold value.

An intake system for use with an internal combustion engine having one or more cylinders. The intake system including a compressor assembly having an inlet and an outlet, and where the outlet is configured to be open to and in fluid communication with at least one of the one or more cylinders. The intake system also includes a passageway extending between and in fluid communication with the inlet and the outlet and configured to direct a first flow of gasses and a controller in operable communication with the compressor assembly. Where the intake system is operable in a first mode in which the majority of gasses of the first flow of gasses flow through the passageway toward the outlet, and a second mode in which the majority of gasses of the first flow of gasses flow through the passageway toward the inlet.

A selective catalytic reduction system control system (10) and method of its use include an ammonia (“NH.sub.3”) slip sensor (13) located within an interior space (27) of an exhaust stack (15) of a selective catalytic reactor (31), toward an inlet end (25) of the stack (15); a housing (17) located within the interior space of the exhaust stack; the housing including face panels 19; a nitrogen oxides (“NOx”) sensor (11) contained within an interior space (29) defined by the face panels of the housing, at least two of the face panels (19.sub.I, 19.sub.O) containing an oxidation catalyst; and a dosing controller (59) in communication with the NH.sub.3 and NOx sensors, the dosing controller including a microprocessor with dosing logic embedded thereon. The housing with oxidation catalyst acts as a linear box, isolating the NOx sensor from NH.sub.3 slip, linearizing the NOx sensor signal.

A controller for an internal combustion engine is configured to execute a rich air-fuel ratio control for performing fuel injection while setting a target equivalence ratio such that, at recovery from a fuel cutoff process, an air-fuel ratio of air-fuel mixture is richer than a stoichiometric air-fuel ratio. The controller is configured to execute a target equivalence ratio setting process for setting the target equivalence ratio that is maintained during execution of the rich air-fuel ratio control such that the target equivalence ratio increases as an air excess ratio that is calculated from an output value of a second air-fuel ratio sensor at start of the rich air-fuel ratio control increases.

A method includes: interpreting first oxygen data acquired by a first nitrous oxide (NOx) sensor indicative of a first amount of oxygen in an exhaust flow at a location in or proximate to an exhaust aftertreatment system, wherein the exhaust aftertreatment system is in exhaust gas receiving communication with an engine; estimating an amount of oxygen in the exhaust flow entering the exhaust aftertreatment system from the engine based on engine operation data; and, determining that the NOx sensor is faulty based on determining that a difference between the first amount of oxygen and the estimated amount of oxygen is greater than a threshold value.

A transport refrigeration unit (TRU) is provided and includes a power generation unit, a catalytic element, a tubular element fluidly interposed between the power generation unit and the catalytic element and a control System. The control System is disposed and configured to control operations of the power generation unit in accordance with readings of sensed characteristics of fluid flows between the power generation unit and the catalytic element.