PURPOSE: To effect recirculation of exhaust gas in reliable manner throughout the entire operational range of engine, by employing an arrangement in which recirculation of exhaust gas is effected through two separate lines, that is, exhaust gas is recirculated during high-load operation of engine to an inlet side of blower compressor where pressure is low, while it is recirculated during low-load operation of engine to a port located on the upstream side of throttle valve.
CONSTITUTION: One end of low-load exhaust gas recirculating passage 17 is connected to exhaust passage 16 extending to exhaust turbine 5 and the other end is connected to port 18 formed in main pipe 9 of intake manifold 2 at a position thereof located on the upstream side of the closed position of throttle valve 10. In the passage 17, there are provided an orifice 20 and a recirculation control valve 19 which is opened when negative pressure in intake manifold 2 is increased. On the other hand, one end of high-load exhaust gas recirculating passage 21 is connected to exhaust passage 16 extending to exhaust turbine 5 and the other end is connected to an inlet side of blower compressor 6 where pressure is low. In this passage 21, there are provided an orifice 23 and a recirculation control valve 22 which is opened when pressure in intake manifold 2 is increased.
MORIMOTO NORIO
MASAMOTO YASUSADA
MUNETOKI HIROSHI
