An exhaust gas recirculation system is configured to recirculate a large
amount of exhaust gas to an engine intake passage while reducing
contamination inside the intake passage caused by the recirculated
exhaust gas and prevent damage to the intake passage caused by the heat
of the recirculated exhaust gas. A first recirculation path recirculates
exhaust gas from an upstream section of the exhaust passage located
upstream of a catalytic converter unit. A second recirculation path
recirculates exhaust gas from a downstream section of the exhaust passage
located downstream of the catalytic converter unit. A control unit is
provided that controls the switching of a selector valve between the
first and the second recirculation paths based on the temperature of the
recirculated exhaust gas.