| 摘要 |
There is provided an exhaust gas recirculation device for an engine, which is capable of reducing the emission of NOx and preventing engine overheat when an engine is operated at low to normal high loads. An intake passage (15) for supplying air to a cylinder of an engine (12) is connected to an intake port (14) of the engine, and an exhaust passage (17) for discharging exhaust gas in the cylinder into the atmosphere is connected to an exhaust port (16) of the cylinder. An external EGR device (21) has an EGR passage (21a) one end of which is connected to the exhaust passage and the other end of which is connected to the intake passage and an EGR valve (21b) capable of opening and closing the EGR passage, and an internal EGR device introduces exhaust gas into the cylinder through the exhaust passage by opening an exhaust valve for opening and closing the exhaust port at the time of intake stroke of the cylinder. An EGR cooler (21c) for cooling exhaust gas by using cooling water of the engine is provided in the EGR passage. A controller controls the external EGR device based on the detection output of a temperature sensor (45). |
