Exhaust gas recirculation system for internal combustion engines

摘要

An exhaust gas recirculation system for internal combustion engines comprises an exhaust gas recirculating passage for tapping engine exhaust gas from an exhaust pipe and feeding back to an engine intake pipe downstream of a throttle valve disposed therein, a control valve for opening and closing the recirculating passage in response to a pressure signal, and a throttle port formed in the intake pipe at such position that the port lies upstream of the throttle valve at the fully closed position thereof while lying downstream of the throttle valve when it is opened to a predetermined opening angle. A pressure control valve is provided for controlling the pressure signal to be transmitted to the control valve in accordance with a pressure in the intake pipe downstream of the throttle valve, a pressure derived from the throttle port and a pressure in a pressure cell provided in the recirculating passage upstream of the control valve, thereby to control the exhaust gas recirculation rate fed back to the intake pipe in consideration of the operating load conditions and the revolution number of the engine.