| 摘要 |
During the operation of the internal combustion engine, the reducing agent (11) is transported, as required, from a reducing agent reservoir (12) to a metering valve (17) by means of a reducing agent pump (13), via a reducing agent line (14, 16), and is introduced into a mixing chamber (21) where it is mixed with gas, especially with air. Said mixture is supplied under pressure from the mixing chamber (21), via a mixture line (27), to the exhaust gases of the internal combustion engine. Once the internal combustion engine has been stopped, the reducing agent pump (13) is switched off and the metering valve (17) is opened. Gas is then introduced into the mixing chamber (21), and a bypass line (19) which goes round the reducing agent pump (13) is opened for a pre-determined length of time, so that the mixing chamber (21), the mixture line (27), the metering valve (17), and the reducing agent line (14, 16) are at least partially filled with the gas. In this way, said components are reliably prevented from being damaged by the freezing of the reducing agent. |
