Exhaust Gas Recirculation
A relatively simple way to reduce the amount of nitrogen oxides is exhaust gas recirculation. Part of the exhaust gases are returned to the intake manifold using a valve system. The amount of returned gases is dosed depending on the engine load. Since the exhaust gases contain an insignificant amount of combustible substances, their recirculation affects the temperature reduction in the combustion chamber and at the same time reduces the formation of nitrogen oxides.
The F-type engine with single-point injection system of Bendix and Renault 19 with diesel are equipped with a device for recirculation of exhaust gases. The device for recirculation of exhaust gases reduces the content of nitrogen oxides in the exhaust by mixing 10-15% of gaseous wastes back into the intake air.
The passage from the exhaust manifold to the intake manifold opens under certain conditions. The vacuum line opens only when the coolant exceeds a certain temperature. For this purpose, a thermostatic valve is installed in the engine housing. The low pressure prevailing in the diaphragm valve stops only when the engine has developed approximately 2/3 of the maximum number of revolutions. In gasoline engines, this process is regulated by an electromagnetic valve; in a diesel engine, a spring-pressed diaphragm valve of low pressure from the vacuum pump of the brake booster. The process is controlled by the control device of the gasoline injection system and, accordingly, the regulating valve of the high-pressure fuel pump of the diesel engine.
(Information is located on the website: «renaultbook.ru»)