EXHAUST GAS RECIRCULATION DEVICE

摘要

PROBLEM TO BE SOLVED: To enhance the reduction efficiency of a nitrogen oxide through exhaust gas recirculation by recirculating the exhaust gas in an inlet system at an early stage of starting an engine in an exhaust gas recirculation device. SOLUTION: An exhaust gas recirculation pipe 20 is provided with an exhaust gas recirculation(EGR) cooler 21 for cooling an exhaust gas. Provided is a bypass pipe 23 branched from the exhaust gas recirculation pipe 20 in the downstream of the EGR cooler 21 and merged with an exhaust pipe 18. An EGR valve 24 is mounted on the exhaust gas recirculation pipe 20. A change-over 25 is mounted on the bypass pipe 23. The EGR valve 24 is fully closed in a cold state of an engine and the change-over valve 25 is fully opened to lead the exhaust gas into the EGR cooler 21 and warm engine cooling water, for accelerating the warming up the engine.