An exhaust emission control system of an engine including a NO.sub.x catalyst disposed in an exhaust passage and for storing NO.sub.x within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NO.sub.x when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes a SCR catalyst disposed downstream of the NO.sub.x catalyst and for purifying NO.sub.x by causing a reaction with ammonia, and a processor configured to execute a NO.sub.x reduction controlling module for controlling the air-fuel ratio to a target ratio so that the stored NO.sub.x is reduced. The controlling module limits the performance of the NO.sub.x reduction control when a temperature of the SCR catalyst is above a given temperature and loosens the limitation in a given engine operating state in which an exhaust gas flow rate is above a given rate despite the SCR catalyst temperature.

A system and an approach for determining various flows in an internal combustion engine, such as an amount of recirculation exhaust gas flow through a controlled valve and a fresh air mass flow to an intake of an engine. Also, among the sensors accommodated in the system, is an inexpensive but slow-responding lambda sensor in the exhaust stream.

An exhaust treatment system comprising: a first oxidation catalyst to oxidize nitrogen compounds and/or hydrocarbon compounds in said exhaust stream; a first dosage device downstream of said first oxidation catalyst to supply a first additive into said exhaust stream; a first reduction catalyst device downstream of said first dosage device for reduction of nitrogen oxides in said exhaust stream using said first additive; a particulate filter, comprising a catalytically oxidizing coating downstream of said first reduction catalyst device to catch soot particles and oxidize one or several of nitrogen oxide and incompletely oxidized carbon compounds in said exhaust stream; a second dosage device downstream of said particulate filter to supply a second additive into said exhaust stream; and a second reduction catalyst device downstream of said second dosage device for a reduction of nitrogen oxides in said exhaust stream, using at least one of said first and second additive.

A method is provided for controlling the injection, by a reductant injector in an exhaust system for an internal combustion engine, of reductant for an exhaust aftertreatment unit of the exhaust system, for example a selective catalytic reduction (SCR) unit. The method includes determining a reductant injection debt in dependence on a reductant flow according to at least a first request being higher than a threshold of the reductant flow, and, at least partly in dependence on the reductant injection debt, controlling the reductant injector so as to inject a compensation flow.

An exhaust gas flow control system disclosed relates to the field of mechanical engineering. The system reduces exhaust gas back pressure exerted on an internal combustion engine and prevents excessive heat loss in a radiator. The system comprises a flow regulator connected to an outlet of a silencer and configured to selectively direct the flow of exhaust gases to a metal hydride heat pump and/or a tailpipe. The flow of exhaust gases is directed towards the metal hydride heat pump in case of increased cooling requirement in the vehicle, and to the tailpipe in case of no cooling requirement or maintenance of the metal hydride heat pump. In case of reduced cooling requirement, partial flow of exhaust gases is directed to the metal hydride heat pump and the remaining to the tailpipe. A diverter is configured within the flow regulator to selectively direct the flow of exhaust gases.

A system and an approach for determining various pressures or flows in an internal combustion engine, such as a pressure adjacent a recirculation exhaust gas flow through a controlled valve of an engine. Also, among the sensors accommodated in the system, is a pressure sensor sensing a pressure in an intake manifold of the engine.

Disclosed is a particulate matters sensor device detecting particulate matters (PM) included in exhaust gas, including: a detecting device having detecting electrodes formed on an external peripheral surface of a base having a bar shape with a circular cross section at a predetermined interval in a predetermined direction to sense the particulate matters included in the exhaust gas.

Methods and systems are provided for treatment of an exhaust stream that comprises nitrogen oxides NO.sub.x. The method comprises supplying a first additive to the exhaust stream as a first reduction of a first amount of nitrogen oxides NO.sub.x.sub._.sub.1 reaching a first device, arranged to impact the first amount of nitrogen oxides NO.sub.x.sub._.sub.1. The method also comprises supplying a second additive to the exhaust stream, which is used as a second reduction of a second amount of nitrogen oxides NO.sub.x.sub._.sub.2 reaching a second device, arranged to reduce the second amount of nitrogen oxides NO.sub.x.sub._.sub.2. At least one of the first supply and the second supply is controlled, based on a total ability for the first device to provide the first reduction, and for the second device to provide the second reduction, so that a required total reduction on the nitrogen oxides NO.sub.x in the exhaust stream is provided.

An exhaust treatment system comprising: a first oxidation catalyst to oxidize nitrogen- and/or hydrocarbon compounds in an exhaust stream; a first dosage device downstream of said first oxidation catalyst to supply a first additive into said exhaust stream; a first reduction catalyst device, arranged downstream of said first dosage device, including a slip-catalyst primarily for reduction of nitrogen oxides (NOx), and secondarily for oxidation of additive; a second oxidation catalyst arranged downstream of said first reduction catalyst; a particulate filter arranged downstream of said oxidation catalyst; a second dosage device, arranged downstream of said particulate filter to supply a second additive into said exhaust stream; and a second reduction catalyst device, arranged downstream of said second dosage device for reduction of nitrogen oxides in said exhaust stream, with the use of at least one of said first and said second additive.

An exhaust treatment system comprising: a first dosage device to supply a first additive into an exhaust stream; a first reduction catalyst device downstream of said first dosage device, including a slip-catalyst primarily for reduction of nitrogen oxides (NOx) through the use of the additive, and secondarily for oxidation of additive; an oxidation catalyst downstream of said first reduction catalyst device; a particulate filter downstream of said oxidation catalyst; a second dosage device downstream of said particulate filter to supply a second additive into said exhaust stream; a second reduction catalyst device downstream of said second dosage device for a reduction of nitrogen oxides in said exhaust stream using at least one of said first and said second additive.