Abstract: A method and an apparatus for reducing harmful emissions in the exhaust gases of an internal combustion engine which may be a Diesel engine or an Otto engine operated by a lean fuel air mixture. The exhaust gases are subjected to a catalytic treatment for oxidizing carbon monoxide and hydrocarbons, and the exhaust gases are throttled to increase their temperature under operative conditions of heat deficiency such as at cold start. The exhaust gases are subjected to an additional catalytic treatment for reducing nitrogen oxides in a deoxidation means. The throttling of the exhaust gases is controlled such that the temperature of the exhaust gases will be within a predetermined temperature range at which said deoxidation means is operative.

Abstract: In order to reduce the exhaust gas emissions of automotive vehicle combustion engines including exhaust gas catalytic converters, the exhaust gases are caused to flow between the engine and the catalytic converter through conduit branches of different thermal caracteristics. Said conduit branches comprise a full load tube and a partial load tube, with the full load tube surrounding the partial load tube so as to provide an annular space between the full load tube and the partial load tube.

Abstract: A shut-off or throttle valve comprises a housing (12) defining a flow passage and a valve flap (18) to be pivoted about an axis of rotation (20) extending across the flow cross-section of the valve. The valve flap (18) in its closed position is located in a closing plane containing said axis of rotation and extending transversely to the direction of fluid flow and is spaced at its edges in all positions from the housing such that the respective spacing cannot be overcome by thermal expansions to be expected in operation. The peripheral portions of the valve flap (18) cooperate with abutment edges (34, 36) serving as a front seal. The flap surface is subdivided by the axis of rotation (29) into a pair of sections. Each section has associated therewith an abutment edge (34, 36) extending towards the axis of rotation (20), such that the abutment edges (34, 36) are positioned on opposite sides of the valve flap (18).

Abstract: In order to reduce the exhaust gas emissions of automotive vehicle combustion engines including exhaust gas catalytic converters, the exhaust gases are caused to flow between the engine and the catalytic converter through conduit branches of different thermal characteristics. Said conduit branches comprise a full load tube and a partial load tube, with the full load tube surrounding the partial load tube so as to provide an annular space between the full load tube and the partial load tube.

Abstract: In order to reduce the exhaust gas emissions of an internal combustion engine (10) for automotive vehicles including an exhaust gas catalytic converter (18), a ram condition will be generated at least during the starting phase in the exhaust gas conduit (16), which ram condition provides for an increase of pressure at the exhaust gas outlet of the engine of at least 0.5 bar, preferably of at least 1 bar, and the engine is additionally loaded at rapid load and speed changes.