A post-treatment system includes two SCRs, a second SCR is connected to a booster in parallel, and a three-way valve is arranged before the second SCR and the booster, such that whether an exhaust gas flows through the second SCR or the booster is controlled by means of controlling the three-way valve. In the case of a low temperature, the three-way valve is controlled to close a branch of the booster, such that the exhaust gas flows through the second SCR and a first SCR that are connected in series, thereby reducing the energy loss caused by the exhaust gas flowing through the booster, and improving the NO.sub.x conversion efficiency in the case of a low temperature. In a case of a high temperature, the three-way valve is controlled to close a by-pass line, such that the exhaust gas flows through the booster and the first SCR.

A method for controlling exhaust flow in an EATS of a vehicle. A NO.sub.x sensor output parameter is monitored. It is determined that the NO.sub.x sensor output parameter is below a limit. When the NO.sub.x sensor output parameter is below the limit, it is determined that a first part of the exhaust flow should bypass at least a first area of the SCR unit and that a second part of the exhaust flow should be inputted to at least the first area of the SCR unit. It is initiated that the first part is bypassed and that the second part is inputted to at least the first area of the SCR unit. An amount of reductant that should be added to the second part of the exhaust flow is determined. Addition of the amount of reductant is initiated.

An engine controller includes processing circuitry configured to execute catalyst accelerated activation control by performing a first process that maintains an open degree of a wastegate valve at a specified first open degree and then performing a second process that changes the open degree of the wastegate valve to an open degree that differs from the first open degree.

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.

The disclosure relates to an exhaust gas aftertreatment system with a turbine arranged in the exhaust gas line and with a main catalytic converter arranged downstream from the turbine, wherein the exhaust gas line has a bypass line and a bypass connector, wherein the bypass line opens downstream from the turbine, wherein a main particle filter and, in the bypass line, a catalytic converter are provided, wherein the bypass valve a1) is formed as a three-way valve is and forms the bypass connector a2) the bypass valve is formed as a three-way valve and is provided at the opening b1) is positioned in the bypass line, wherein an exhaust gas flap is provided upstream from the opening in the exhaust gas line b2) the exhaust gas line is formed without exhaust gas flaps downstream from the bypass connector and upstream from the opening, and the catalytic converter has a three-way coating or the respective main catalytic converter has a DOC coating.

An exhaust gas purification device includes a first catalyst, a second catalyst, a bypass pipe, a hydrocarbon adsorbent, and a switching controller. The first catalyst is provided in an exhaust pipe. The second catalyst is provided downstream of the first catalyst in the exhaust pipe. The bypass pipe branches from a first portion of the exhaust pipe. The first portion is located upstream of the second catalyst. The bypass pipe is recoupled to a second portion of the exhaust pipe. The second portion is located upstream of the second catalyst. The hydrocarbon adsorbent is provided in the bypass pipe. The switching controller is configured to switch a flow path of an exhaust gas to the bypass pipe based on a deterioration degree of the first catalyst.

The exhaust gas after-treatment system of an engine configured as a gas engine or as a dual-fuel engine includes a catalyst, that can be flowed through by exhaust gas, a control tube extending through a recess in the catalyst, which control tube is movable relative to the catalyst and is flowable through by exhaust gas, and an actuator which is equipped to move the control tube relative to the catalyst dependent on at least one operating condition of the engine and/or at least one operating condition of the exhaust gas after-treatment system such that in a first relative position of the control tube relative to the catalyst, the catalyst can be flowed through by exhaust gas but not the control tube, and in a second relative position of the control tube relative to the catalyst, the control tube can be flowed through by the exhaust gas but not the catalyst.

An internal combustion engine has a humidity sensor that is disposed in an intake passage of the internal combustion engine, a temperature sensor configured to detect an intake air temperature in a position of the humidity sensor, and a controller configured to correct an offset error of the sensor value by adding a correction value to the sensor value. The controller is configured to acquire the intake air temperatures respectively at a plurality of timings in a process of the intake air temperature changing, acquire the sensor values at the respective plurality of timings, calculate values excluding influences of temperature differences of the intake air temperatures from the respective sensor values as humidity index values respectively, and determine a correction value so that a variation degree of the humidity index values becomes small.

A method for controlling the operation of an exhaust aftertreatment system (EATS) in a vehicle is described. The EATS comprises a main SCR catalyst and a pre-SCR catalyst, a pre-injector arranged upstream the pre-SCR catalyst for providing reductant, a bypass channel fluidly connected to the fluid channel and arranged to bypass the pre-SCR-catalyst and the pre-injector, and a valve configured to control a split of exhaust gases between the pre-SCR catalyst and the bypass channel. The method includes determining the amount of ammonia stored in the pre-SCR catalyst; determining the temperature of the main SCR catalyst; when the ammonia storage in the pre-SCR catalyst is below an ammonia storage threshold and the temperature of the main SCR catalyst is above a temperature threshold, injecting reductant by the pre-injector and controlling the valve to allow a flow of exhaust gases to the pre-SCR catalyst sufficient for transporting the injected reductant to the pre-SCR catalyst for increasing the ammonia storage.

An engine controller includes processing circuitry configured to execute catalyst accelerated activation control by performing a first process that maintains an open degree of a wastegate valve at a specified first open degree and then performing a second process that changes the open degree of the wastegate valve to an open degree that differs from the first open degree.