초록 ▼

An exhaust system for a vehicular lean-burn internal combustion engine includes a NOx reduction catalyst, a source reductant, means (20) for contacting the catalyst with the reductant, means for sensing the temperature of the exhaust gas and/or the catalyst bed and means, when in use, for controllin

An exhaust system for a vehicular lean-burn internal combustion engine includes a NOx reduction catalyst, a source reductant, means (20) for contacting the catalyst with the reductant, means for sensing the temperature of the exhaust gas and/or the catalyst bed and means, when in use, for controlling reductant addition. The reductant addition control means supplies an amount of reductant to the catalyst at a rate corresponding to a measured temperature value of the exhaust gas and/or catalyst bed, which temperature value has been pre-determined to correlate, in use, with an amount of NOx in the exhaust gas.

대표청구항 ▼

The invention claimed is: 1. An exhaust system for exhausting a gas composition from a vehicular lean-burn internal combustion engine, which system comprising a catalyst for reducing NOx in an exhaust gas to N2 with a suitable reductant, a source of reductant, means for contacting the NOx reduction

The invention claimed is: 1. An exhaust system for exhausting a gas composition from a vehicular lean-burn internal combustion engine, which system comprising a catalyst for reducing NOx in an exhaust gas to N2 with a suitable reductant, a source of reductant, means for contacting the NOx reduction catalyst with the reductant, an oxidation catalyst disposed downstream of the NOx reduction catalyst, means for determining a temperature difference (ΔT) across the oxidation catalyst, and means for controlling reductant addition, wherein the reductant addition control means controls reductant addition at a rate sufficient to maintain ΔT within a pre-determined range, wherein the system is configured so that the exhaust gas composition over the oxidation catalyst is lean.