| 摘要 |
<p>A combustion engine is provided with an exhaust gas after treatment device, which comprises a first selective catalytic reduction (SCR) device (20), a second SCR device (40) downstream of the first SCR device and a diesel particulate filter (DPF) (30) located between the first SCR device and the second SCR device. The operating temperature range of the first SCR device is different to the operating temperature range of the second SCR device. A method of dosing the exhaust gas after treatment device comprises the steps of: allowing dosing of the first SCR device with reductant only when a temperature of the first SCR device is within the operating temperature range of the first SCR device; and allowing dosing of the second SCR device with reductant only when a temperature of the second SCR device is within the operating temperature range of the second SCR device; and reducing the level of dosing of the first SCR device when regeneration of the DPF is required. Furthermore, a controller configured to perform this method is provided.</p> |
