Disclosed are systems, methods, and algorithms for monitoring and indicating filter life. In particular, the disclosed systems, methods, and algorithms may be utilized for monitoring and indicating the useful life of a filter in an internal combustion engine.

A heavy duty truck includes a diesel engine, an exhaust after-treatment system, and an engine control unit. The exhaust after-treatment system may include one or more selective catalytic reduction systems, each with a respective heater, and each heater with a respective pair of temperature sensors, one upstream and the other downstream of the heater. Such systems may be used to perform diagnostic methods including populating a lookup table having heat energy supplied to an exhaust gas stream by the diesel engine as a first independent variable, heat energy supplied to the exhaust gas stream by a heater as a second independent variable, and a resulting temperature as an output. Such a lookup table can be used to maintain a temperature of the exhaust gas flow at a constant target temperature.

An exhaust gas purification system of engine configured to classify a PM accumulation state of DPF into multiple evaluation stages based on a plurality of evaluation indices, and to repeatedly perform determination of the current evaluation stage by the current stage determination part and determination of whether to move up the current evaluation stage to the evaluation stage of the next rank by the evaluation stage determination part, wherein upon a defect of a sensor among different types of sensors being detected by the defect detection part, the current evaluation stage is newly redetermined by the current stage redetermination part as substituted for the current evaluation stage determined by the current stage determination part.

A method for controlling regeneration a catalyst by an exhaust gas purification device includes: measuring a temperature of exhaust gas flowing into a first catalyst unit; estimating a NO.sub.x amount loaded into the first catalyst unit and a slip amount of NO.sub.x of the first catalyst unit by using the temperature and an amount of the exhaust gas of the first catalyst unit; calculating a temperature of a second catalyst unit by using the temperature of the first catalyst unit; and estimating a NO.sub.x amount flowing into the second catalyst unit by using at least one of the slip amount of NO.sub.x of the first catalyst unit and the temperature of the second catalyst unit.

Systems and methods for controlling a dosing of reductant for an internal combustion engine system including a catalyst are disclosed. The method includes measuring a value indicative of inlet temperature of the catalyst. When the inlet temperature is less than or equal to a first threshold, the method includes adjusting the dosing of reductant according to a first process. When the inlet temperature is greater than the first threshold, the method includes adjusting the dosing of reductant according to a second process, the second process being different than the first process.

A method for controlling a return valve of an exhaust system and to an exhaust system with a control unit which is configured to carry out the method. The method is based on the object of avoiding an overpressure in the line system for urea solution as a result of a reduction in the injection rate. The method includes the steps of determining whether one or more of the following states are present during the operation of the exhaust system: a) an injection rate per unit of time of urea solution of the dosing valve is less than or equal to a predefined injection limit, b) a pressure measured by the pressure sensor in the line system overshoots a predefined first upper pressure limit (P2). The return valve is opened for a first predefined opening duration (Δt1) if states a) and b) are present and at least one of the states has already been present for at least a predefined period of time (Δta). The return valve is closed after the first predefined opening duration (Δt1) has elapsed.

A hybrid electric vehicle and a catalyst heating control method are configured to select a point in time at which catalyst heating control is performed and to perform a follow-up measure based on the selected point in time. The catalyst heating control method includes performing mode switching from a first mode in which only a drive motor is used as a driving source to a second mode in which an engine is driven in a state in which a drive shaft and the engine are disconnected from each other to start heating of a catalyst of the engine. When demand torque higher than a maximum output of the drive motor occurs before the catalyst heating is completed, the second mode is maintained until the demand torque is greater than the sum of the maximum output and a predetermined margin.

Controllers and methods for managing transitions into and/or out of a cylinder cut off mode are described. In some embodiments, a skip fire based transition into a cylinder cut off mode is used in which the fraction of working cycles that are fired is gradually reduced to a threshold firing fraction. Once the threshold firing fraction has been reached, all of the working chambers are deactivated.

A system comprising an aftertreatment system comprising: a catalyst member, and a first exhaust conduit upstream of the catalyst member; a first temperature sensor operatively coupled to the catalyst member; a flow sensor coupled to the first exhaust conduit; and a controller. The controller determines a temperature of the catalyst member, a flow rate of exhaust within the first exhaust conduit, and a space velocity of the exhaust within the catalyst member. The controller determines a first degradation value indicative of a degradation of the catalyst member. The controller determines a first difference between the first degradation value and a first degradation reference value and a second difference between the first degradation value and a second degradation reference value. After determining that the first difference is less than the second difference, the controller selects a first calibration metric. The controller determines a first efficiency value associated with the catalyst member.

A method for operating an internal-combustion engine having an exhaust gas catalyst, a first exhaust gas sensor upstream of the exhaust gas catalyst and a second exhaust gas sensor downstream of the exhaust gas catalyst. A fill level of an exhaust gas component that can be stored in the exhaust gas catalyst is determined using a theoretical catalyst model, into which, as the input value, a signal of the first exhaust gas sensor (a first signal); a signal of the second exhaust gas sensor (a second signal); and a target signal are provided. The target signal corresponds to the signal that would be expected at the determined fill level in the exhaust gas catalyst. The catalyst model is reinitiated when the deviation of the second signal from the target signal exceeds a predetermined threshold value. The fill level is also regulated, and an air-fuel mixture is adjusted.