Exhaust Gas Recirculation
A relatively simple way to reduce the amount of nitrogen oxides is exhaust gas recirculation. Part of the exhaust gases is returned through the valve system to the intake manifold. The amount of returned gases is dosed depending on the load on the engine. Since the exhaust gases contain a small amount of combustible substances, their recirculation has the effect of lowering the temperature in the combustion chamber and at the same time reducing the formation of nitrogen oxides.
Engine type «F» with a single-point injection system, Vendix and Renault 19 with a diesel engine are equipped with an exhaust gas recirculation device. The exhaust gas recirculation device reduces the content of nitrogen oxides in the exhaust by re-admixing 10-15% of the gaseous waste with the intake air.
The passage from the exhaust to the intake manifold opens under certain conditions. The vacuum line opens only when the coolant exceeds a certain temperature. For this, a thermostatic valve is installed in the motor housing. The underpressure prevailing in the diaphragm valve stops only when the engine has developed approximately 2/3 of the maximum number of revolutions. For gasoline engines, this process is regulated by a solenoid valve, for a diesel engine, a low-pressure diaphragm valve pressed by a spring from the vacuum pump of the brake booster. The process is controlled by the control device for the gasoline injection system and, accordingly, the control valve of the diesel high-pressure fuel pump.