The most important requirements for the application of EGR systems to direct-injection gasoline engines are high EGR rates and good dynamic response. High exhaust emissions and rough running of the engine are thus avoided during sudden load changes. Electrically actuated EGR valves specifically developed for direct-injection gasoline engines offer, besides a wide dynamic range, good actuation characteristics and low system costs and are thus capable of meeting the principal requirements of this application.
In addition to fast acting EGR valves, it is essential to keep dead volumes within EGR systems as small as possible. Designs with a decentralised EGR return straight into the runners of the intake system meet this requirement, and have the additional advantages of lower contamination and lower thermal stress on the intake manifold.
Precise control of EGR rates over a wide range of operating conditions, combined with tight tolerances for all operating modes and over the entire service life, requires a combination consisting of both position and air mass control of the EGR system to achieve required dynamics, control accuracy and diagnostic capabilities.
Professional integration of the EGR system into the intake module allows the creation of cost-effective and durable solutions, which are also functionally optimal. Here, the appropriate development partner must have know-how in the areas of exhaust gas recirculation and air mass measurement as well as air guidance and air mass control.