939003487 - 1080C EXHAUST GAS RECIRCULATION SYSTEM (E.G.R.)
CONSTRUCTION SPECIFICATIONS
This system makes it possible to send some (5 - 15%) of the exhaust gases to the intake in certain operating conditions.This lowers the peak temperature in the combustion chamber restricting the formation of nitrogen oxides (NOx).The E.G.R. solenoid valve (1) operated by the injection control unit (2) carries out the task of reintroducing some of the exhaust gases taken from the exhaust manifold (4) back into the engine intake.A heat exchanger (3) makes it possible to partly cool the exhaust gases increasing the volumetric output of the engine.1 - EGR solenoid2 - Injection control unit3 - Heat exchanger4 - Exhaust manifold5 - Intake chamber
OPERATION
At coolant temperatures of > 20°C with the engine speed between 800 and 3000 rpm, the injection control unit operates the E.G.R. solenoid valve with a square wave signal.The variation in this signal allows the E.G.R. coil to move a shutter, thereby regulating the flow of exhaust gases from the exhaust manifold to the intake manifold; there are two results:
- less air is introduced;
- the combustion temperature is reduced (on account of the presence of inert gases) resulting in a decrease in the formation of NOx (nitrogen oxides).
DESCRIPTION OF COMPONENTS
E.G.R. SOLENOID VALVE
The Pierburg E.G.R. solenoid valve, fitted on the intake manifold, has the task of modulating the flow of exhaust gases to the intake according to the command from the injection control unit.This modulation takes place by means of the internal solenoid, with PWM operation by the control unit, which activates the control rod via the internal valve.1 - E.G.R. valve casing2 - Internal valve3 - Gas intake from exhaust manifold4 - Gas outlet to intake manifold