Diesel engine exhaust gas recirculation control system

摘要

An exhaust gas recirculation control system for a vehicle diesel engine with an exhaust gas recirculation passage, including: a fluid pressure operated exhaust gas recirculation valve which controls flow resistance of the recirculation passage according to a control fluid pressure supplied thereto so as to increase the flow resistance up to a maximum substantially infinite value as the control fluid pressure approaches atmospheric pressure; an electrically operated switching over valve, which, when actuated, changes over the control fluid pressure supplied to the exhaust gas recirculation control valve to atmospheric pressure, and an exhaust gas recirculation control signal generating system which generates the control fluid pressure supplied to the exhaust gas recirculation control valve to operate it regularly as well as an electrical signal which actuates the switching over valve when the rate of change of engine load is greater than a certain predetermined value.