| 摘要 |
PCT No. PCT/GB92/01035 Sec. 371 Date Dec. 10, 1993 Sec. 102(e) Date Dec. 10, 1993 PCT Filed Jun. 10, 1991 PCT Pub. No. WO92/22734 PCT Pub. Date Dec. 23, 1992.A method is described for reducing the total emissions during cold starts from an engine burning a hydrocarbon fuel and having an afterburner arranged upstream of a catalytic converter. The method comprises the steps of: (i) adding an excess of fuel to the engine combustible charge and adding air to the engine exhaust gases immediately after the engine has first fired to assure the presence in the exhaust/air mixture of sufficient concentrations of hydrogen and oxygen to permit the resulting exhaust/air mixture to be ignitable and to burn with a steady flame in the afterburner while the latter is at a temperature close to the ambient temperature, and (ii) igniting the exhaust/air mixture in the afterburner immediately after the engine has first fired. In the preferred embodiment of the invention, the excess fuel and/or the additional air are regulated after ignition has occurred in the afterburner to maintain a steady flame in the afterburner until at least part of the matrix of the catalytic converter has reached its light off temperature. |
