Apparatus for controlling emission from IC engine comprises regenerating NOx catalyzer in internal combustion engine exhaust by keeping catalyzer near target temperature and heating it whenever engine is at low load

摘要

The heater (28) heats the NOx catalyzer (20) to establish a target temperature based on the mode of operation of the engine as detected by the detector (33, 36). The heater does not heat the NOx catalyzer if the engine is running at high load when it is not appropriate to heat the NOx catalyzer. Apparatus for controlling the emission from an internal combustion engine (1). This comprises a NOx catalyzer (20) which adsorbs and accumulates the NOx from the exhaust gases flowing in the NOx catalyzer if the air/fuel ratio is poorer than the stoichiometric ratio and which releases the NOx when the air/fuel ratio is the same as or richer than the stoichiometric ratio. A heater (28) heats the NOx catalyzer if it is necessary to suppress the sulfur oxides in the NOx catalyzer; and means of detecting the state of operation (33, 36) of the internal combustion engine. If it is necessary to suppress the sulfur oxide in the NOx catalyzer, the heater temporarily raises the temperature of the NOx catalyzer to the temperature required for recovery from sulfur poisoning and, if the recovery has not been achieved by a final preset time, the heater heats the NOx catalyzer to a target temperature based on the state of operation of the engine detected by the detector and, if the engine is in an operating state during which heating is not appropriate, the heater stops heating the NOx catalyzer. The target temperature of the catalyzer is made higher if the engine is operating with low load than if the engine is operating with high load. The command to turn on the heater is weakened if the real temperature of the catalyzer is higher than the target temperature and strengthened if the real temperature of the catalyzer is below the target temperature. The heater stops if the engine's mode of operation does not allow suppression of sulfur oxide to occur during a preset time while the heater heats the catalyst. An Independent claim is also included for process for using the apparatus, where the mode of operation of the engine is detected, a target temperature for the NOx catalyzer is established based on the mode of operation and the NOx catalyzer is heated to the target temperature or the heating is stopped if the engine is operating with high load when it is not appropriate to heat the NOx catalyzer.