Device for controlling the air-fuel ratio of the operating mixture to be introduced into the combustion chambers of a self-igniting internal combustion engine

A device is proposed in which the quantity of fuel fed in, the quantity of fresh air required for combustion of this quantity of fuel and the quantity of returned exhaust gas required for residual filling of the cylinder can be precisely determined by simple means. Firstly, orifice gauges (6, 7) are used for this purpose in the intake pipe (2) and in the fuel line (3), which is supplied by a fuel feed pump (8) at constant pressure, which orifice gauges control a valve (42), which adjusts the particular ratio required between the fresh air and the returned exhaust gas, by way of a four-chamber differential pressure valve (5). Secondly, pneumatic actuators are used for this purpose both for the fuel supply (56) and for the exhaust gas return (69), which are adjusted by means of a control logic (74) by way of electro-pneumatic control valves (58, 71) as a function of the fresh air feed (62).