Exhaust gas recirculation control device for diesel engine

Abstract

An exhaust gas recirculation control device in a diesel engine, capable of suppressing NOx and smoke discharged. A first temperature sensor () is provided at a portion more on the upstream side than a portion where a suction air path () joins an exhaust gas recirculation path (), and a second temperature sensor () is provided on the downstream side. Further, an engine load detection sensor () and an engine speed detection sensor () are arranged. The exhaust gas recirculation control device also has memory means where the temperature of suction air before it is mixed with an exhaust gas and a temperature value at a second temperature sensor installation position are previously memorized, the temperature value corresponding to an appropriate exhaust gas recirculation amount that is uniquely defined by an engine load and an engine speed. Further, judging means is provided. The judging means compares the corresponding temperature value memorized in the memory means and a value detected by the second temperature sensor. When the detected value is within a predetermined range relative to the temperature value, a circulation exhaust gas amount is determined to be appropriate, and when the detected value is not within a predetermined range relative to the temperature value, a circulation exhaust gas amount is determined to be abnormal.