Apparatus and method for exhaust gas recirculation

A method of operating an internal combustion engine, equipped with an exhaust-gas recirculation device that recirculates exhaust gases of the internal combustion engine into an intake region of the internal combustion engine, wherein the exhaust-gas recirculation device comprises:

• (a) at least one exhaust-gas cooler through which a first flow path for recirculation of exhaust gas runs and which has at least one first cooling stage and at least one additional cooling stage;
• (b) at least one flap arrangement by which the at least one additional cooling stage is activatable;
• (c) a bypass line through which a second flow path for the recirculation of exhaust gas runs and by which the exhaust-gas cooler can be bypassed during the recirculation of exhaust gas;
• and
• (d) an EGR valve having at least three possible positions:
• (1) a rest position, in which the exhaust-gas recirculation device is closed,
• (2) a first position, in which the first flow path through the exhaust-gas cooler is open, and
• (3) a second position, in which the second flow path through the bypass line is open,
• the method comprising the acts of:
• a) operating the internal combustion engine without exhaust-gas recirculation by shutting off the exhaust-gas recirculation device, with the EGR valve set in the rest position;
• b) exhaust-gas recirculation during a low-load phase, wherein the exhaust-gas recirculation takes place through the bypass line, with the EGR valve set in the second position, wherein no cooling of the recirculated exhaust gas takes place;
• c) exhaust-gas recirculation during load operation, wherein the exhaust-gas recirculation takes place through the exhaust-gas cooler, with the EGR valve set in the second position;
• and
• d) enabling at least one additional cooling stage by the at least one flap arrangement if high-load operation is present.