DE2130436

1349088 Purifying I C engine exhaust gases UNIVERSAL OIL PRODUCTS CO 28 June 1971 [29 June 1970] 30155/71 Heading F1B Exhaust gases from an I.C. engine, e.g. a spark-ignition but especially a compressionignition engine of a vehicle, are delivered through a converter 1 having a catalyst bed 12 therein. Secondary fuel from a tank 5 is introduced through injector 6 when the temperature of the converter, during warm up, is insufficient for efficient catalystic conversion but sufficient to initiate combustion of the secondary fuel without separate ignition (e.g. above 316‹C). Thus the temperature of the converter is raised to a high value (e.g. 399‹C) at which the introduction of secondary fuel is stopped until the temperature falls to say 385‹C. The means controlling the introduction of secondary fuel comprises a fuel pump 4 and a temperature sensor 2 which controls operation of the pump via a switch 3. Alternatively, or additionally, the fuel tank may be pressurized so that the introduction of secondary fuel can be controlled by a valve 31 via switch 3 and sensor 2. There may be two injectors 6 and the sensor 2 may be located in inlet 10. The sensor may be replaced by one which senses a temperature-dependent condition of the engine, e.g. fuel pressure of throttle setting. The secondary fuel is turned off when the engine is inoperative by means associated with the ignition switch of the vehicle. The secondary fuel may be Diesel fuel, propane, butane, pentane, hexane, octane, methanal, ethanol, acetane, methyl ethyl ketone or mixtures of these.