A selective catalytic reduction (SCR) catalyst is disposed in an exhaust gas system of an internal combustion engine. A reductant injector is coupled to the exhaust gas stream at a position upstream of the SCR catalyst, and first and second NO.sub.x sensors provide NOx measurements upstream of and downstream of the SCR catalyst, respectively. A system and method is disclosed for operating the system to determine a NOx amount and/or a NH3 slip amount downstream of the SCR catalyst by decoupling NOx-NH3 measurements from the output of the second NOx sensor to provide control of the reductant injection amount.

An internal combustion engine (ICE) and method of control are provided to determine a value of a catalyst temperature and a value of a quantity of a reducing agent stored in the catalyst. The quantity of gas recirculated by an exhaust gas recirculation (EGR) system of the ICE is calculated on the basis of the value of the catalyst temperature and of the value of the quantity of the reducing agent stored in the catalyst. This solution makes it possible to adjust the quantity of gas recirculated by the EGR system on the basis of parameters linked to an efficiency of a selective catalytic reduction (SCR) system associated with the ICE, in order to reduce the global quantity of pollutants produced by the ICE and released in the environment.

An exhaust purification device for an internal combustion engine is provided with an NO.sub.x adsorbent for adsorbing NO.sub.x in exhaust gas and an NO.sub.x purifying catalyst for purifying NO.sub.x in exhaust gas, which are arranged in an engine exhaust passage. An electric heater is provided for raising the temperature of the NO.sub.x adsorbent. When a signal requesting startup of an internal combustion engine is issued, the device starts to supply electric power to the electric heater before the internal combustion engine completely warms up, and supplies the electric heater with a quantity of electric power making the temperature of the NO.sub.x adsorbent equal to or higher than the moisture desorption temperature but lower than the NO.sub.x desorption temperature.

The present invention relates to a wall flow filter, to a method for the production and the use of the filter for reducing harmful exhaust gases of an internal combustion engine. Particle filters are commonly used for filtering exhaust gases from a combustion process. Also disclosed are novel filter substrates and their specific use in exhaust gas aftertreatment.

A skip fire engine controller and method of control is described wherein during transitions from a first firing density to a second firing density, a firing density and a pumping density are separately set so as to balance the conflicting demands of (a) torque control, (b) Noise, Vibration and Harshness (NVH), (c) air flow through the engine and (d) air-fuel ratio.

The invention relates to an exhaust aftertreatment arrangement (100) for an exhaust system of an internal combustion engine, said exhaust aftertreatment arrangement (100) comprising a fluid passage (30) for exhaust gases from said exhaust system, said fluid passage (30) defining an inner perimeter (32) and an exhaust aftertreatment unit (40) comprising an exhaust aftertreatment element (42) confined by an outer wall (44) defining an outer periphery (46) of the exhaust aftertreatment unit (40), the exhaust aftertreatment unit (40) being sealingly arranged in said fluid passage (30) for enabling flow of said exhaust gases through said exhaust aftertreatment element (42). A leakage treatment member (50) comprising an exhaust aftertreatment component is arranged between said inner perimeter (32) of the fluid passage (30) and said outer periphery (46) of said outer wall (44) of the exhaust aftertreatment unit (40), for aftertreatment of any leakage of said flow of exhaust gases past said aftertreatment unit (40) in said fluid passage (30).

A particulate matter sensor detecting particulate matter in exhaust emissions is provided, which is resistant to having sensor surfaces buried by particulate matter residue. Detection electrodes are provided, with alternating polarity, laminated in a laminating direction, separated by insulation. Of the detection electrodes, first detection electrodes of one polarity and second detection electrodes of the other polarity are exposed perpendicular to the laminating direction. In the direction perpendicular to the laminating direction, the particulate matter sensor has target accumulating parts on which the particulate matter is accumulated. In the target accumulating parts, the thickness W1 of the first detection electrodes in the laminating direction is greater than the thickness W2 of the second detection electrodes in the laminating direction.

A method for checking the operability of a secondary-air system of an internal combustion engine includes measuring a first pressure between a first secondary-air pump and a first master secondary-air valve as well as a second master secondary-air valve, measuring a second pressure between a second secondary-air pump and a first slave secondary-air valve and a second slave secondary-air valve, controlling the first master secondary-air valve and the first slave secondary-air valve together, and controlling the second master secondary-air valve and the second slave secondary-air valve together. A secondary-air system includes a first control and a second control, wherein a first master secondary-air valve and a first slave secondary-air valve are controllable together by the first control and wherein a second master secondary-air valve and a second slave secondary-air valve are controllable together by the second control.

A non-transitory computer-readable medium having a NOx sensor purification instructions for a NOx sensor causes: an on-vehicle electronic computer mounted in the vehicle, when it comes to a predetermined purification time, to execute a start procedure to send a start command to perform a purification control to the control unit; and control unit, in response to the start command, to execute a purification procedure to perform the purification control which causes the current flowing in the reference pump cell from the reference pump current to be a purification pump current, which is set to a current value larger than the reference pump current.

A non-transitory computer-readable medium having a NOx sensor purification instructions for a NOx sensor causes: an on-vehicle electronic computer mounted in the vehicle, when it comes to a predetermined purification time, to execute a start procedure to send a start command to perform a purification control to the control unit; and control unit, in response to the start command, to execute a purification procedure to perform the purification control which causes the current flowing in the reference pump cell from the reference pump current to be a purification pump current, which is set to a current value larger than the reference pump current.