Patent ID: 7987836

Claim:
A system for delivering exhaust gas recirculation (EGR) through a recirculation system to an engine intake manifold, comprising: a first EGR cooler coupled in the recirculation system; a first EGR cooler bypass that bypasses at least the first EGR cooler; a second EGR cooler coupled in the recirculation system; a second EGR cooler bypass that bypasses the second EGR cooler; a plurality of valve elements; and a controller including non-transitory electronic storage medium with programs to adjust the plurality of valve elements to adjust an amount and temperature of EGR delivered to the intake manifold, the valve elements further adjusted in response to a first outlet temperature of the first EGR cooler to adjust bypassing of the first and second EGR coolers differently based on whether any of said first outlet temperature and a second outlet temperature of the second EGR cooler approaches a fouling temperature, wherein the first outlet temperature is a temperature of gases at an outlet of the first EGR cooler but upstream of a point where bypass gases are introduced from the first EGR cooler bypass, and wherein the second outlet temperature is a temperature of gases at an outlet of the second EGR cooler but upstream of a point where bypass gases are introduced from the second EGR cooler bypass.