Development of optimized exhaust gas heating strategies for passenger car Diesel engines by means of variable valve train applications

The cold start and heating phase of passenger car Diesel engines is essential to comply with the actual emission legislation targets. The HC and CO emissions that are produced immediately after a cold start contribute to more than 70 % of the total cycle results. The initially low temperature level of the exhaust gas aftertreatment system components results in a very low conversion efficiency. With a further strengthening of the emission legislation, the first phases of the emission test cycles will become even more important. It is aspired to achieve the required, even fast heat-up of the exhaust aftertreatment without fuel consumption penalties to reduce engine-out emissions efficiently. Application of a variable valve train system (VVT) can be an additional technology to address this challenge.