Exhaust gas recirculation and boost systems

The EGR valve is opened and closed by a controller via an electro-pneumatic pressure transducer. The continuously changing vacuum in the system enables the AGR valve to be opened steplessly. The EGR valve is open at idle and at partial load up to an engine speed of approx. 3000 rpm. At full load and RPM above 3000 RPM the EGR valve is closed, in order to avoid black smoke from the exhaust pipe.

Often diesel engines are equipped with turbochargers with variable intake geometry (the so-called. VTG compressors). They are characterized by high boost pressure even at low engine speeds and quick response to load changes. Such a compressor can be identified by a vacuum actuator placed obliquely to the turbine blades. The boost pressure is adjustable depending on the load, engine speed and ambient pressure according to the set characteristics. At high altitudes above sea level, thus at low ambient pressures, the boost pressure is lowered to avoid overloading the turbocharger.