Control apparatus for internal combustion engine with exhaust gas recirculaton

摘要

In a mechanical type EGR apparatus, an EGR valve receives a negative pressure near a throttle valve and opens/closes an EGR path in response to the negative pressure. An EGR-VM is operated in response to an exhaust gas pressure to control a diaphragm back pressure to be introduced into the EGR valve. A CPU calculates a control amount of an ISC valve in order to obtain an optimum EGR ratio characteristic, depending upon engine operation conditions, and drives the ISC valve based on this control amount. The negative pressure at the negative pressure around the throttle valve is changed when the ISC valve is opened/closed and thus a portion of air into the engine flows through a bypass path, so that the diaphragm back pressure into the EGR valve is controlled to a desired value.