IC engine with exhaust gas turbo system and incorporating catalyser

摘要

A by-pass conduit (12) on the one hand issues upstream of the turbine and on the other hand issues between the turbine and the catalyser in the exhaust gas system. A controllable valve (14) is fitted in the by-pass conduit and devices (15, 18) are provided for controlling the by-pass valve. The by-pass valve control devices at least partially open the valve after the start of the engine during a catalyser heating-up period when the engine load is beneath a predetermined threshold value and close the valve under a load which is above the threshold value. The by-pass valve control devices comprise a dual pressure box (15) with two separate pressure chambers and an operating rod coupled to the by-pass valve and movable dependent upon the difference of the pressures in the two chambers.