Exhaust cleaning unit for remote-ignition internal combustion engine has two 3-way catalytic converters with turbo charger in between and controllable secondary air pump and regulating and measuring devices to reduce toxic emissions

摘要

Exhaust cleaning unit has two 3-way catalytic converters with turbo charger in between and with controllable secondary air pump and regulating and measuring devices to reduce toxic emissions. The first catalytic converter is charged with a rich exhaust gas mixture whilst the second converter is charged with a lean or stoichiometric exhaust gas mixture. A first three-way catalytic converter (22) is provided close to the engine (10) and a second 3-way catalytic converter (24) which is provided away from the engine in the exhaust train with a turbo charger (14) in between. A controllable secondary air pump (28) has in inlet (29) into the exhaust train between the turbo charger and second converter and a measuring and evaluating device measures the composition of the exhaust gas in the region of the converters to determine the air mass flow. The exhaust composition before the first converter is controlled by a control and regulator device so that the composition can be controlled before the second converter through the secondary air pump. The first catalytic converter is charged with a rich exhaust gas mixture whilst the second converter is charged with a lean or stoichiometric exhaust gas mixture.