EGR Cooling System with Multiple EGR Coolers

A method for cooling EGR of an engine, comprising:

• passing at least a portion of the EGR through a catalyst to remove at least some particle matters and/or hydrocarbons in the EGR;
• and then
• passing the portion of EGR through a first cooler, the first cooler having coolant at a first temperature flowing there through;
• and then
• passing the portion of EGR through a second cooler, the second cooler having coolant at a second temperature flowing there through;
• dissipating heat from the portion of EGR through fins in at least one of the first and second coolers;
• and
• circulating the first coolant through an engine coolant loop, and circulating the second coolant through an auxiliary coolant loop, the auxiliary coolant loop being separate from the engine coolant loop, the auxiliary coolant loop including a charge air cooler.

An EGR cooling system for an engine, comprising:

• a water-to-air charge air cooler;
• an engine coolant loop having a first coolant, the first coolant circulated through the engine;
• an auxiliary coolant loop having a second coolant, the second coolant circulated through the charge air cooler as well;
• an integrated EGR cooling unit that includes a first EGR cooler being coupled to the engine coolant loop, and a second EGR cooler being coupled to the auxiliary coolant loop;
• an EGR cooler bypass for bypassing the integrated EGR cooling unit;
• and
• a catalyst configured to trap particulate matters and/or oxidize hydrocarbons in the EGR, the catalyst positioned upstream of the integrated EGR cooling unit and upstream of the EGR cooler bypass.